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Course Title: Data Structures Credits: 3:0 Course Designers: 1. S. Geetha Sgeetha@tce.edu 2. S. Sudha ssj@tce.edu 3. M.K. Kavitha Devi mkkdit@tce.edu Background: Program Outcomes addressed a. An ability to apply knowledge of engineering, information technology, mathematics, and science c. An ability to design a system or component, or process to meet stated specifications d. An ability to identify, formulate and solve engineering problems Competencies 1. Ability to identify and implement appropriate data structure for a given application 2. Comprehend the terms "data abstraction", "abstract data type", and "data structures", and how data structures and algorithms have to be blended carefully to obtain efficient implementations. 3. Explain the notion of time complexity and the asymptotic notions of "Big Oh" with non-trivial examples. 4. Explain the difference between worst case complexity and best case complexity. Justify with an example algorithm for each of the complexities: O(n), O(n*2), O(n*3), O(2**n), O(n log n), O(n*2 log n),O(log n), O(log log n), O(sqrt(n)). 5. Identify all the trade-offs involved in choosing static versus dynamic data structures 6. In the context of searching, identify the trade-offs involved in selecting the most efficient data structure. 7. In the context of sorting, identify the trade-offs involved in selecting: (a) bubble-sort (b) insertion sort (c) selection sort (d) quick sort (e) merge sort (f) heap sort. Formative and Summative Evaluation Bloom’s Category Test 1 Test 2 End-semester examination 1 Recall 30 20 10 2 Comprehension 30 20 10 3 Application 20 30 30 4 Analysis 10 20 20 5 Synthesis 0 0 0 6 Evaluation 10 10 30 Course Level Learning Objectives: Recall 1. What is data structure? 2. List out the areas in which data structures are applied extensively? 3. What are the major data structures used in the following areas: RDBMS, Network data model and Hierarchical data model? 4. What are the notations used in Evaluation of Arithmetic Expressions using prefix and postfix forms? 5. List out few of the applications of tree data-structure? 6. List out few of the applications that make use of Multilinked Structures? 7. What is the bucket size, when the overlapping and collision occur at same time? 8. What are the Collision Resolution Techniques and the methods used in each of the type? 9. Comprehension 1. If you are using C language to implement the heterogeneous linked list, what pointer type will you use? 2. What is the minimum number of queues needed to implement the priority queue? 3. What is the data structure used to perform recursion? 4. How many null branches are there in a binary tree with 20 nodes? 5. What are the methods available in storing sequential files? 6. How many different trees are possible with 10 nodes? 7. What is the condition for balancing to be done in an AVL tree? 8. What is the type of the algorithm used in solving the 8 Queens problem? 9. How do you traverse a given tree using Inorder, Preorder and Postorder traversals. 10. What is the suitable efficient data structure for constructing a tree? 11. There are 8, 15, 13, 14 nodes were there in 4 different trees. Which of them could have formed a full binary tree? 12. At what location can you store the node 4 in a given binary tree using array? 13. Sort the given values using Quick Sort? 65 70 75 80 85 60 55 50 45 14. Classify the Hashing Functions based on the methods by which the key value is found. 15. What is the efficient data structure used in the internal storage representation in RDBM? 16. What are the steps to inserting a new item at the head of a linked list? Use one short English sentence for each step. 17. Suppose that p is a reference to an IntNode in a linked list, and it is not the tail node. What are the steps to removing the node after p? Use one short English sentence for each step. 18. Give one of the Sequence operations that is more efficient because the class keeps a tail reference as a private instance variable. Provide a specific example showing why the operation would be less efficient without the tail reference. 19. Give one of the Sequence operations that is easier to program because the class keeps a precursor (rather than just a cursor). Provide a specific example showing why the operation would be harder to program without the precursor. 20. Write a class definition that could be used to define a node in a doubly linked list. Include only the instance variables, not the methods. Also write one sentence to describe a situation when a doubly linked list is appropriate. 21. Describe a situation where storing items in an array is clearly better than storing items on a linked list. 22. Suppose cursor refers to a node in a linked list (using the IntNode class with instance variables called data and link). What statement changes cursor so that it refers to the next node? A. cursor++; B. cursor = link; C. cursor += link; D. cursor = cursor.link; 23. Suppose cursor refers to a node in a linked list (using the Node class with instance variables called data and link). What boolean expression will be true when cursor refers to the tail node of the list? A. (cursor == null) B. (cursor.link == null) C. (cursor.data == null) D. (cursor.data == 0.0) E. None of the above. 24. Which boolean expression indicates whether the numbers in two nodes (p and q) are the same. Assume that neither p nor q is null. A. p == q B. p.data == q.data C. p.link == q.link D. None of the above. 25. Suppose that p is a reference variable that contains the null reference. What happens at runtime if the program tries to activate a method of p? A. IllegalArgumentException B. IllegalStateException C. NullPointerException D. The results are unpredictable. 26. Suppose that a method has one node as a parameter and it returns two references to nodes. What's the best header for the method? A. IntNode foo(IntNode p) B. IntNode, IntNode foo(IntNode p) C. IntNode[ ] foo(IntNode p) D. void foo(IntNode p, IntNode answer1, IntNode answer2) 27. Suppose that the Bag is implemented with a linked list. Which of these operations are likely to have a constant worst-case time? A. add B. countOccurrences C. remove D. None of (A), (B), and (C) have a constant worst-case time E. TWO of (A), (B), and (C) have a constant worst-case time F. ALL of (A), (B), and (C) have a constant worst-case time 28. Explain what modifications would be needed to make the parenthesis matching algorithm check expressions with more kinds of parentheses such as <>. Application 1. Convert the expression ((A + B) * C - (D - E) ^ (F + G)) to equivalent Prefix and Postfix notations. 2. Draw the B-tree of order 3 created by inserting the following data arriving in sequence - 92 24 6 7 11 8 22 4 5 16 19 20 78 3. Draw a binary Tree for the expression : A * B - (C + D) * (P / Q) 4. Is a Linked List a linear or non-linear data structure? 5. Suppose we are using the usual IntNode class (with instance variables called data and link). Your program is using an IntNode variable called head to refer to the first node of a linked list (or head is null for the empty list). Write a few lines of C++ code that will print all the double numbers on the list? 6. Suppose we are using the usual IntNode class (with instance variables called data and link), and that locate is referring to a node in a linked list. Write an assignment statement that will make locate refer to the next node in the list (if there is one). If there is no next node, then your assignment statement should set locate to null. 7. Suppose that p, q, and r are all references to nodes in a linked list with 15 nodes. The variable p refers to the first node, q refers to the 8th node, and r refers to the last node. Write a few lines of code that will make a new copy of the list. Your code should set THREE new variables called x, y, and z so that: x refers to the first node of the copy, y refers to the 8th node of the copy, and z refers to the last node of the copy. Your code may NOT contain any loops, but it can use the other IntNode methods. 8. Suppose that a and b are IntNode variables. Write one clear sentence to when the expression (a==b) is true? 9. What is the output of these statements, using your Sequence ADT implemented as a linked list: a. DoubleLinkedSeq x = new DoubleLinkedSeq( ); b. DoubleLinkedSeq y = new DoubleLinkedSeq( ); c. x.addBefore(41); // Inserts 41 into the list x d. x.addBefore(42); // Inserts 42, so that x is now 42, 41 with cursor at front e. y = (DoubleLinkedSeq) x.clone( ); f. x.addAfter(43); // Attaches 43 so that x is now 42, 43, 41 with cursor at 43 g. y.advance( ); h. System.out.println("y size is " + y.size( )); 10. What is the expression for generating a pseudorandom number in the range 1...N? a. (int) (Math.random() * N); b. (int) (Math.random() / N); c. (int) (Math.random() * (N + 1)); d. (int) (Math.random() / (N + 1)); e. (int) (Math.random() * N) + 1; 11. Which expression computes a pseudorandom integer between -10 and 10 using rand() from stdlib.h? a. (int) (Math.random( ) * 20) – 10 b. (int) (Math.random( ) * 21) – 10 c. (int) (Math.random( ) * 22) – 10 d. (int) (Math.random( ) * 20) – 11 e. (int) (Math.random( ) * 21) - 11 Evaluation 1. Compare the worst-case big-O time analysis for these two methods: The add method for the Bag that is implemented using an array, and the add method for the Bag that is implemented using a linked list. 2. Compare the worst-case big-O time analysis for these two methods: The remove method for the Bag that is implemented using a fixed-sized array, and the remove method for the Bag that is implemented using a linked list. 3. Compare the worst-case big-O time analysis for these two methods: The addBefore method for the Sequence that is implemented using an array, and the addBefore method for the Sequence that is implemented using a linked list. 4. Compare the worst-case big-O time analysis for these two methods: The remove method for the Sequence that is implemented using an array, and the remove method for the Sequence that is implemented using a linked list. 1. Complete the body of this method. You do not need to check the precondition. You may use the CharStack class. public static boolean balanced(String p) // Precondition: Each character of p is '(', ')', '{' or '}'. // Postcondition: The method returns true if the characters form a // sequence of correctly balanced parentheses with each '(' matching // a ')' and each '{' matching a '}'. Note that a sequence such as // ( { ) } is NOT balanced because when we draw lines to match the // parentheses to their partners, the lines cross each other. On the // other hand, ( { } ) and { ( ) } are both balanced. I am going to execute this code with THREE pushes and ONE pop: IntStack s = new IntStack( ); s.push(1); s.push(2); s.push(3); System.out.println(s.pop( )); Suppose that s is represented by a partially filled array. Draw the state of the private instance variables of s after the above code: _______ __________________________________ manyItems| | data| | | | | | |_______| |______|______|______|______|______|... [0] [1] [2] [3] [4] I am going to execute this code with THREE pushes and ONE pop: IntStack s = new IntStack( ); s.push(1); s.push(2); s.push(3); System.out.println(s.pop( )); Suppose that s is represented by a linked list. Draw the state of the private member variables of s after the above code: _______ head| | |_______| 2. Implement the following method. You may use the IntStack class and the Stack operations of push, pop, peek, isEmpty, and size. The parameter, in, is an EasyReader from Appendix B of the text and it is already attached to some kind of input. You may use the methods: o in.isEOLN() -- returns true when the end of line is reached. o in.peek() -- returns the next input character without actually reading it. o in.ignore() -- reads and throws away the next input character. o in.intInput() -- reads and returns an integer value from the EasyReader. This should be used only if you know that the next input characters form a valid integer value. The method specification is: public static int evaluatePostfix(EasyReader in) // Precondition (Which is not checked): The next input line of in is a // properly formed postfix expression consisting of integers, // the binary operations + and -, and spaces. // Postcondition: The method has read the next input line (including // the newline) and returned the value of the postfix expression. 3. Consider the usual algorithm to convert an infix expression to a postfix expression. Suppose that you have read 10 input characters during a conversion and that the stack now contains these symbols: || |+| |(| bottom |___*___| Now, suppose that you read and process the 11th symbol of the input. Draw the stack for the case where the 11th symbol is: A. A number: B. A left parenthesis: C. A right parenthesis: D. A minus sign: E. A division sign: Multiple Choice 1. Entries in a stack are "ordered". What is the meaning of this statement? A. A collection of Stacks can be sorted. B. Stack entries may be compared with the '<' operation. C. The entries must be stored in a linked list. D. There is a first entry, a second entry, and so on. 2. The operation for adding an entry to a stack is traditionally called: A. add B. append C. insert D. push 3. The operation for removing an entry from a stack is traditionally called: A. delete B. peek C. pop D. remove 4. Which of the following stack operations could result in stack underflow? A. is_empty B. pop C. push D. Two or more of the above answers 5. Which of the following applications may use a stack? A. A parentheses balancing program. B. Keeping track of local variables at run time. C. Syntax analyzer for a compiler. D. All of the above. 6. Consider the following pseudocode: declare a stack of characters while ( there are more characters in the word to read ) { read a character push the character on the stack } while ( the stack is not empty ) { pop a character off the stack write the character to the screen } What is written to the screen for the input "carpets"? A. serc B. carpets C. steprac D. ccaarrppeettss 7. Here is an INCORRECT pseudocode for the algorithm which is supposed to determine whether a sequence of parentheses is balanced: declare a character stack while ( more input is available) { read a character if ( the character is a '(' ) push it on the stack else if ( the character is a ')' and the stack is not empty ) pop a character off the stack else print "unbalanced" and exit } print "balanced" Which of these unbalanced sequences does the above code think is balanced? A. ((()) B. ())(() C. (()())) D. (()))() 8. Consider the usual algorithm for determining whether a sequence of parentheses is balanced. What is the maximum number of parentheses that will appear on the stack AT ANY ONE TIME when the algorithm analyzes: (()(())(()))? A. 1 B. 2 C. 3 D. 4 E. 5 or more 9. Consider the usual algorithm for determining whether a sequence of parentheses is balanced. Suppose that you run the algorithm on a sequence that contains 2 left parentheses and 3 right parentheses (in some order). What is the maximum number of parentheses that will ever appear on the stack AT ONE TIME during the computation? A. 1 B. 2 C. 3 D. 4 E. 5 or more 10. Suppose we have an array implementation of the stack class, with ten items in the stack stored at data[0] through data[9]. The CAPACITY is 42. Where does the push method place the new entry in the array? A. data[0] B. data[1] C. data[9] D. data[10] 11. Consider the implementation of the Stack using a partially-filled array. What goes wrong if we try to store the top of the Stack at location [0] and the bottom of the Stack at the last used position of the array? A. Both peek and pop would require linear time. B. Both push and pop would require linear time. C. The Stack could not be used to check balanced parentheses. D. The Stack could not be used to evaluate postfix expressions. 12. In the linked list implementation of the stack class, where does the push method place the new entry on the linked list? A. At the head B. At the tail C. After all other entries that are greater than the new entry. D. After all other entries that are smaller than the new entry. 13. In the array version of the Stack class, which operations require linear time for their worst-case behavior? A. is_empty B. peek C. pop D. push when the stack is below capacity E. None of these operations require linear time. 14. In the linked-list version of the Stack class, which operations require linear time for their worst-case behavior? A. is_empty B. peek C. pop D. push E. None of these operations require linear time. 15. What is the value of the postfix expression 6 3 2 4 + - *: A. Something between -15 and -100 B. Something between -5 and -15 C. Something between 5 and -5 D. Something between 5 and 15 E. Something between 15 and 100 16. Here is an infix expression: 4+3*(6*3-12). Suppose that we are using the usual Stack algorithm to convert the expression from infix to postfix notation. What is the maximum number of symbols that will appear on the stack AT ONE TIME during the conversion of this expression? A. 1 B. 2 C. 3 D. 4 E. 5 QUEUES 1. Complete the body of this method. Use a CharQueue to store the input line as it is being read. The parameter is an EasyReader from Appendix B of the text. Use the method in.charInput( ) to read and return the next character of the EasyReader, and use in.isEOLN( ) to determine whether the next input character is the end-of-line. public static int counter(EasyReader in) // Precondition: There is a line of input waiting to be read from in. // Postcondition: A line of input has been read from in, up to but not // including the newline character. The return value of the method // is the number of times that the LAST character of the line appeared // somewhere in this line. // EXAMPLE Input: ABBXDXXZX // The value returned by counter would be 4 for this input since there // are 4 X's in the input line. i. I am going to execute this code with THREE inserts and ONE get_front: IntQueue q = new IntQueue( ); q.insert(1); q.insert(2); q.insert(3); System.out.println(q.getFront( )); Suppose that q is represented by a circular array. Draw the state of these private instance variables of q after the above code: _______ __________________________________ front| | data| | | | | | |_______| |______|______|______|______|______| [0] [1] [2] [3] [4] ii. I am going to execute this code with THREE insert and ONE get_front: IntQueue q = new IntQueue( ); q.insert(1); q.insert(2); q.insert(3); System.out.println(q.getFront( )); Suppose that q is represented by a linked list. Draw the state of the private instance variables of q after the above code: _______ front| | |_______| _______ rear| | |_______| 2. Describe why it is a bad idea to implement a linked list version a queue which uses the head of the list as the rear of the queue. 3. Suppose that you want to implement the PriorityQueue so that insertions occur in constant time, but getFront requires linear time. You will use these class definitions, where the data entering the PriorityQueue is a String and the priorities are ints. public class PriorityQueue { // A PriorityNode is a node from a linked list of strings, with // methods for getString, setString, getPriority, setPriority, // getLink, and setLink. private PriorityNode head; public void insert(String entry, int priority)... public String getFront( )... ... } (A) Write ONE sentence to describe how the insert method will work (with constant time). (B) Then implement the getFront method (which will have linear worst-case time). In your implementation, you DO NOT have to worry about items with equal priority (they may come out of the prioirty queue however you like, without necessarily having FIFO behavior). To remove the head node of a linked list, use the assignment: head = head.getLink( ); Multiple Choice 1. One difference between a queue and a stack is: A. Queues require linked lists, but stacks do not. B. Stacks require linked lists, but queues do not. C. Queues use two ends of the structure; stacks use only one. D. Stacks use two ends of the structure, queues use only one. 2. If the characters 'D', 'C', 'B', 'A' are placed in a queue (in that order), and then removed one at a time, in what order will they be removed? A. ABCD B. ABDC C. DCAB D. DCBA 3. Which of the following expressions evaluates to true with approximate probability equal to P? (P is double and 0 <= P <= 1). A. Math.random() < P B. Math.random() > P C. Math.random() < P * 100 D. Math.random() > P * 100 4. Suppose we have a circular array implementation of the queue class, with ten items in the queue stored at data[2] through data[11]. The current capacity is 42. Where does the insert method place the new entry in the array? A. data[1] B. data[2] C. data[11] D. data[12] 5. Consider the implementation of the Queue using a circular array. What goes wrong if we try to keep all the items at the front of a partially-filled array (so that data[0] is always the front). A. The constructor would require linear time. B. The getFront method would require linear time. C. The insert method would require linear time. D. The isEmpty method would require linear time. 6. In the linked list implementation of the queue class, where does the insert method place the new entry on the linked list? A. At the head B. At the tail C. After all other entries that are greater than the new entry. D. After all other entries that are smaller than the new entry. 7. In the circular array version of the Queue class, which operations require linear time for their worst-case behavior? A. getFront B. insert when the capacity has not yet been reached C. isEmpty D. None of these operations require linear time. 8. In the linked-list version of the Queue class, which operations require linear time for their worst-case behavior? A. getFront B. insert C. isEmpty D. None of these operations require linear time. 9. If data is a circular array of CAPACITY elements, and rear is an index into that array, what is the formula for the index after rear? A. (rear % 1) + CAPACITY B. rear % (1 + CAPACITY) C. (rear + 1) % CAPACITY D. rear + (1 % CAPACITY) 10. I have implemented the queue with a circular array, keeping track of front, rear, and manyItems (the number of items in the array). Suppose front is zero, and rear is one less than the current capacity. What can you tell me about manyItems? A. manyItems must be zero. B. manyItems must be equal to the current capacity. C. count could be zero or the capacity, but no other values could occur. D. None of the above. 11. I have implemented the queue with a linked list, keeping track of a front node and a rear node with two reference variables. Which of these reference variables will change during an insertion into a NONEMPTY queue? A. Neither changes B. Only front changes. C. Only rear changes. D. Both change. 12. I have implemented the queue with a linked list, keeping track of a front node and a rear node with two reference variables. Which of these reference variables will change during an insertion into an EMPTY queue? A. Neither changes B. Only front changes. C. Only rear changes. D. Both change. 13. Suppose getFront is called on a priority queue that has exactly two entries with equal priority. How is the return value of getFront selected? A. One is chosen at random. B. The one which was inserted first. C. The one which was inserted most recently. D. This can never happen (violates the precondition) 14. An array of queues can be used to implement a priority queue, with each possible priority corresponding to its own element in the array. When is this implementation not feasible? A. When the number of possible priorities is huge. B. When the number of possible priorities is small. C. When the queues are implemented using a linked list. D. When the queues are implemented with circular arrays. SEARCHING 1. Here is an array with exactly 15 elements: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Suppose that we are doing a serial search for an element. Circle any elements that will be found by examining two or fewer numbers from the array. 2. Here is an array with exactly 15 elements: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Suppose that we are doing a binary search for an element. Circle any elements that will be found by examining two or fewer numbers from the array. 3. Implement the body of the following function using a binary search of the array. You do not need to check the precondition. All your local variables must be size_t variables. bool has_42(const int data[ ], size_t n) // Precondition: The elements data[0]...data[n-1] are sorted from smallest // to largest. The value of n might be zero (indicating an empty // array). // Postcondition: A true return value indicates that the number 42 appears in // data[0]...data[n-1]. A false return value indicates that 42 doesn’t appear. 4. Draw a hash table with open addressing and a size of 9. Use the hash function "k%9". Insert the keys: 5, 29, 20, 0, 27 and 18 into your table (in that order). 5. Suppose you are building an open address hash table with double hashing. The hash table capacity is n, so that the valid hash table indexes range from 0 to n. Fill in the blanks: o In order to ensure that every array position is examined, the value returned by the second hash function must be ________________________ with respect to n. o One way to ensure this good behavior is to make n be _______________, and have the return value of the second hash function range from _________ to _________ (including the end points). 6. You are writing code for the remove member function of a chained hash table. Fill in the blanks in this pseudocode with the two missing statements. You may use pseudocode yourself, or write actual C++ code: void Table::remove(int key) { Node cursor; size_t i; 1. i = hash(key); 2. Make cursor point to the node that contains an item with the given key (or set it to NULL if there is no such node). 3. if (cursor != NULL) { 3a. ____________________________________________________________ _ 3b. ____________________________________________________________ _ } 7. Draw a hash table with chaining and a size of 9. Use the hash function "k%9" to insert the keys 5, 29, 20, 0, and 18 into your table. 8. Suppose that I have the following record_type definition for a record in a hash table: struct record_type { int key; ... other stuff may also appear here ... }; The hash table uses open addressing with linear probing. The table size is a global constant called CAPACITY. Locations of the table that have NEVER been used will contain the key -1. Locations of the table that were once used but are now vacant will contain the key -2. All valid keys will be non-negative, and the hash function is: size_t hash(int key) { return (key % CAPACITY); } Complete the implementation of the following function. There is no need to check the precondition, but your code must be as efficient as possible. bool key_occurs(const record_type data[ ], int search_key) // Precondition: data[0]...data[CAPACITY-1] is an open address hash table // as described above. // Postcondition: If search_key occurs as a key of a record in the table, then // the function returns true; otherwise the function returns false. 9. Suppose that an open-address hash table has a capacity of 811 and it contains 81 elements. What is the table's load factor? (An appoximation is fine.) 10. I plan to put 1000 items in a hash table, and I want the average number of accesses in a successful search to be about 2.0. A. About how big should the array be if I use open addressing with linear probing? NOTE: For a load factor of A, the average number of accesses is generally ½(1+1/(1-A)). B. About how big should the array be if I use chained hashing? NOTE: For a load factor of A, the average number of accesses is generally (1+A/2). Multiple Choice 1. What is the worst-case time for serial search finding a single item in an array? A. Constant time B. Logarithmic time C. Linear time D. Quadratic time 2. What is the worst-case time for binary search finding a single item in an array? A. Constant time B. Logarithmic time C. Linear time D. Quadratic time 3. What additional requirement is placed on an array, so that binary search may be used to locate an entry? A. The array elements must form a heap. B. The array must have at least 2 entries. C. The array must be sorted. D. The array's size must be a power of two. 4. What is the best definition of a collision in a hash table? A. Two entries are identical except for their keys. B. Two entries with different data have the exact same key. C. Two entries with different keys have the same exact hash value. D. Two entries with the exact same key have different hash values. 5. Which guideline is NOT suggested from from empirical or theoretical studies of hash tables: A. Hash table size should be the product of two primes. B. Hash table size should be the upper of a pair of twin primes. C. Hash table size should have the form 4K+3 for some K. D. Hash table size should not be too near a power of two. 6. In an open-address hash table there is a difference between those spots which have never been used and those spots which have previously been used but no longer contain an item. Which function has a better implementation because of this difference? A. insert B. is_present C. remove D. size E. Two or more of the above functions 7. What kind of initialization needs to be done for an open-address hash table? A. None. B. The key at each array location must be initialized. C. The head pointer of each chain must be set to NULL. D. Both B and C must be carried out. 8. What kind of initialization needs to be done for an chained hash table? A. None. B. The key at each array location must be initialized. C. The head pointer of each chain must be set to NULL. D. Both B and C must be carried out. 9. A chained hash table has an array size of 512. What is the maximum number of entries that can be placed in the table? A. 256 B. 511 C. 512 D. 1024 E. There is no maximum. 10. Suppose you place m items in a hash table with an array size of s. What is the correct formula for the load factor? A. s + m B. s - m C. m - s D. m * s E. m / s COMPLEXITY 1. Why is the order of an algorithm generally more important than the speed of the processor? 2. Convert each time formula to the best possible big-O notation. Do not include any spurious constants in your big-O answer. Time Formula Big-O 10n . 2n² . 3 times log (base 2) of n . 2n² + 10n . 3. What does a run-time analysis usually count? A. The number of arithmetic and other operations required for the program to run B. The number of megabytes required for the program to run C. The number of seconds required for the program to run D. The number of seconds plus the number of megabytes E. The number of seconds times the number of megabytes 4. Which of these is the correct big-O expression for 1+2+3+...+n A. O(log n) B. O(n) C. O(n log n) D. O(n²) 4. Which of the following formulas in big-O notation best represent the expression n²+35n+6? A. O(n³) B. O(n²) C. O(n) D. O(42) 5. Answer true or false for this statement: For all possible inputs, a linear algorithm to solve a problem must perform faster than a quadratic algorithm to solve the same problem. TRUE. FALSE. 6. Answer true or false for this statement: True or false: An algorithm with worst case time behavior of 3n takes at least 30 operations for every input of size n=10. TRUE. FALSE. 7. What term is used to describe an O(n) algorithm. A. Constant B. Linear C. Logarithmic D. Quadratic 8. Here is some code for an integer variable n: while (n > 0) { n = n/10; // Use integer division } What is the worst-case time analysis for the above loop? A. O(1) B. O(log n) C. O(n) D. O(n²) 9. Express the formula (n - 2)*(n - 4) using big-O notation: A. O(1) B. O(8) C. O(log n) D. O(n) E. None of the above TREES 1. Here is a small binary tree: 14 / \ 2 11 / \ / \ 1 3 10 30 / / 7 40 Circle all the leaves. Put a square box around the root. Draw a star around each ancestor of the node that contains 10. Put a big X through every descendant of the node that contains 10. 2. Draw a full binary tree with at least 6 nodes. 3. Draw a complete binary tree with exactly six nodes. Put a different value in each node. Then draw an array with six components and show where each of the six node values would be placed in the array (using the usual array representation of a complete binary tree). 4. Write the instance variables for a new class that could be used for a node in a tree where: (1) Each node contains int data, (2) Each node has up to four children, and (3) Each node also has a reference to its parent. Store the references to the children in an array of four components. 5. Draw a binary taxonomy tree that can be used for these four animals: Rabbit, Horse, Whale, Snake. 6. Using the BTNode class from Chapter 9, write a new static method of the BTNode class to meet the following specification. No recursion is needed. public static void subswap(BTNode root) // Precondition: Root is the root reference of a binary tree. // Postcondition: If root is non-null, then the original left subtree below // this root has been moved and is now the right subtree, and the original // right subtree is now the left subtree. // Example original tree: Example new tree: // 1 1 // / \ / \ // 2 3 3 2 // / \ / \ // 4 5 4 5 7. Redo the previous problem as a new non-static BTNode method. 8. Using the BTNode class from Chapter 9, write a new static method of the BTNode class to meet the following specification. public static void flip(BTNode root) // Precondition: Root is the root reference of a binary tree. // Postcondition: If the root is non-null, then the tree below this node is // now the mirror image of its original value. // Example original tree: Example new tree: // 1 1 // / \ / \ // 2 3 3 2 // / \ / \ // 4 5 5 4 9. Redo the previous problem as a new non-static BTNode method. 10. Here is a small binary tree: 14 / \ 2 11 / \ / \ 1 3 10 30 / / 7 40 Write the order of the nodes visited in: A. An in-order traversal: B. A pre-order traversal: C. A post-order traversal: 11. Suppose IntBTNode is a BTNode (from Chapter 9) with integer data. Write a new static method of the IntBTNode class to meet the following specification . public static void increase(IntBTNode root) // Precondition: root is the root reference of a binary tree. // Postcondition: Every node of the tree has had its data // increased by one. 12. Redo the previous problem as a new non-static BTNode method. 13. Using the BTNode class from Chapter 9, write a new static method of the BTNode class to meet the following specification. public static int manyNodes(BTNode root) // Precondition: root_ptr is the root reference of a binary tree. // Postcondition: The return value is the number of nodes in the tree. // NOTES: The empty tree has 0 nodes, and a tree with just a root has // 1 node. 14. Using the BTNode class from Chapter 9, write a new static method of the BTNode class to meet the following specification. public static int treeDepth(BTNode root) // Precondition: root_ptr is the root reference of a binary tree. // Postcondition: The return value is the depth of the binary tree. // NOTES: The empty tree has a depth of -1 and a tree with just a root // has a depth of 0. 15. Suppose IntBTNode is a BTNode (from Chapter 9) with integer data. Write a new static method of the IntBTNode class to meet the following specification. public static int count42(IntBTNode root) // Precondition: root is the root reference of a binary tree (but // NOT NECESSARILY a search tree). // Postcondition: The return value indicates how many times 42 appears // in the tree. NOTE: If the tree is empty, the method returns zero. 16. Suppose IntBTNode is a BTNode (from Chapter 9) with integer data. Write a new static method of the IntBTNode class to meet the following specification. public static boolean has42(IntBTNode root) // Precondition: root is the root reference of a binary tree (but // NOT NECESSARILY a search tree). // Postcondition: The return value indicates whether 42 appears somewhere // in the tree. NOTE: If the tree is empty, the method returns false. 17. Suppose IntBTNode is a BTNode (from Chapter 9) with integer data. Write a new static method of the IntBTNode class to meet the following specification. public static boolean all42(IntBTNode root) // Precondition: root is the root reference of a binary tree (but // NOT NECESSARILY a search tree). // Postcondition: The return value is true if every node in the tree // contains 42. NOTE: If the tree is empty, the method returns true. 18. Suppose IntBTNode is a BTNode (from Chapter 9) with integer data. Write a new static method of the IntBTNode class to meet the following specification . public static int sum(IntBTNode root) // Precondition: root is the root reference of a binary tree. // Postcondition: The return value is the sum of all the data in all the nodes. // NOTES: The return value for the empty tree is zero. 19. Suppose that we want to create a binary search tree where each node contains information of some data type. What additional factor is required for the data type? 20. Suppose that a binary search tree contains the number 42 at a node with two children. Write two or three clear sentences to describe the process required to delete the 42 from the tree. 21. Suppose IntBTNode is a BTNode (from Chapter 9) with integer data. Write a new static method of the IntBTNode class to meet the following specification. Make the method as efficient as possible (do not visit nodes unnecessarily). public static int count42(BTNode root) // Precondition: root is the root reference of a binary SEARCH tree. // Postcondition: The return value indicates how many times 42 appears // in the tree. 22. Suppose IntBTNode is a BTNode (from Chapter 9) with integer data. Write a new static method of the IntBTNode class to meet the following specification. Make the method as efficient as possible (do not visit nodes unnecessarily). public static int max(BTNode root) // Precondition: root is the root reference of a nonempty binary SEARCH // tree. // Postcondition: The return value is the largest value in the tree. 23. Suppose IntBTNode is a BTNode (from Chapter 9) with integer data. Write a new static method of the IntBTNode class to meet the following specification. Make the method as efficient as possible (do not visit nodes unnecessarily). void insert42(BTNode root) // Precondition: root is the root reference of a binary SEARCH tree. // Postcondition: One copy of the number 42 has been added to the binary // search tree. Multiple Choice 1. There is a tree in the box at the top of this section. How many leaves does it have? A. 2 B. 4 C. 6 D. 8 E. 9 2. There is a tree in the box at the top of this section. How many of the nodes have at least one sibling? A. 5 B. 6 C. 7 D. 8 E. 9 3. There is a tree in the box at the top of this section. What is the value stored in the parent node of the node containing 30? A. 10 B. 11 C. 14 D. 40 E. None of the above 4. There is a tree in the box at the top of this section. How many descendants does the root have? A. 0 B. 2 C. 4 D. 8 5. There is a tree in the box at the top of this section. What is the depth of the tree? A. 2 B. 3 C. 4 D. 8 E. 9 6. There is a tree in the box at the top of this section. How many children does the root have? A. 2 B. 4 C. 6 D. 8 E. 9 7. Consider the binary tree in the box at the top of this section. Which statement is correct? A. The tree is neither complete nor full. B. The tree is complete but not full. C. The tree is full but not complete. D. The tree is both full and complete. 8. What is the minimum number of nodes in a full binary tree with depth 3? A. 3 B. 4 C. 8 D. 11 E. 15 9. What is the minimum number of nodes in a complete binary tree with depth 3? A. 3 B. 4 C. 8 D. 11 E. 15 10. Select the one true statement. A. Every binary tree is either complete or full. B. Every complete binary tree is also a full binary tree. C. Every full binary tree is also a complete binary tree. D. No binary tree is both complete and full. 11. Suppose T is a binary tree with 14 nodes. What is the minimum possible depth of T? A. 0 B. 3 C. 4 D. 5 12. Select the one FALSE statement about binary trees: A. Every binary tree has at least one node. B. Every non-empty tree has exactly one root node. C. Every node has at most two children. D. Every non-root node has exactly one parent. 13. Suppose t is a BTNode variable from Chapter 9, which expression indicates that t represents an empty tree? A. (t == null) B. (t->data == 0) C. (t->data == null) D. ((t->left == null) && (t->right == null)) 14. Consider the node of a complete binary tree whose value is stored in data[i] for an array implementation. If this node has a right child, where will the right child's value be stored? A. data[i+1] B. data[i+2] C. data[2*i + 1] D. data[2*i + 2] 15. Suppose that a binary taxonomy tree includes 8 animals. What is the minimum number of NONLEAF nodes in the tree? A. 1 B. 3 C. 5 D. 7 E. 8 16. There is a tree in the box at the top of this section. What is the order of nodes visited using a pre-order traversal? A. 1 2 3 7 10 11 14 30 40 B. 1 2 3 14 7 10 11 40 30 C. 1 3 2 7 10 40 30 11 14 D. 14 2 1 3 11 10 7 30 40 17. There is a tree in the box at the top of this section. What is the order of nodes visited using an in-order traversal? A. 1 2 3 7 10 11 14 30 40 B. 1 2 3 14 7 10 11 40 30 C. 1 3 2 7 10 40 30 11 14 D. 14 2 1 3 11 10 7 30 40 18. There is a tree in the box at the top of this section. What is the order of nodes visited using a post-order traversal? A. 1 2 3 7 10 11 14 30 40 B. 1 2 3 14 7 10 11 40 30 C. 1 3 2 7 10 40 30 11 14 D. 14 2 1 3 11 10 7 30 40 19. Consider this binary search tree: 14 / \ 2 16 / \ 1 5 / 4 Suppose we remove the root, replacing it with something from the left subtree. What will be the new root? A. 1 B. 2 C. 4 D. 5 E. 16 HEAPS 1. Suppose that we want to create a heap where each node contains information of some data type. What additional factor is required for the data type? 2. A heap is a binary tree where the entries can be compared using the usual six comparison operations (that form a total order semantics). Write the two rules that the binary tree must follow in order for the structure to actually be a heap. 3. Give two different reasons to explain why the following binary tree is not a heap: 91 / \ 77 46 / \ \ 68 81 11 4. Draw a new heap that is created by inserting 82 into the following heap: 910 / \ 77 66 / \ / \ 68 1 3 11 5. Draw a new heap that is created by removing one item from the following heap: 910 / \ 77 66 / \ / \ 68 1 3 11 6. Suppose that you are performing a reheapification downward. Write a precise condition that describes the situation that causes the reheapification to stop. 7. Suppose that you are performing a reheapification upward. Write a precise condition that describes the situation that causes the reheapification to stop. 8. Suppose that a non-leaf node in a B-tree contains 42 entries. How many children does the node have? 9. Draw an example of a B-tree with four nodes and seven integer entries. The value of MINIMUM is 1 for this tree. 10. Draw a new B-tree that is created by inserting 82 into the following B-tree. For this example, the minimum number of items in each node is 1. Note that the rightmost leaf starts with two entries, 71 and 93. 56 / \ 7 66 / \ / \ 2 8 63 71 and 93 11. Draw a new B-tree that is created by deleting 63 from the following B-tree. For this example, the minimum number of items in each node is 1. Note that the rightmost leaf starts with two entries, 71 and 93. 56 / \ 7 66 / \ / \ 2 8 63 71 and 93 12. Suppose that a B-tree is declared so that MAXIMUM (the maximum number of items in a node) is 84. What is the value of MINIMUM (the minimum number of items in a non-root node)? 13. Suppose that a B-tree is declared so that MAXIMUM (the maximum number of items in a node) is 84. Write one clear sentence to describe why each node's data array is set up to hold up to 85 items (one more than MAXIMUM). 14. Suppose that a and b are two positive integers and n is some non-negative number. Write an equation to show the relationship between log base a of n and log base b of n. Give a derivation to show that the relationship is valid. Multiple Choice 1. What feature of heaps allows them to be efficiently implemented using a partially filled array? A. Heaps are binary search trees. B. Heaps are complete binary trees. C. Heaps are full binary trees. D. Heaps contain only integer data. 2. If a heap is implemented using a partially filled array called data, and the array contains n elements (n > 0), where is the entry with the greatest value? A. data[0] B. data[n-1] C. data[n] D. data[2*n + 1] E. data[2*n + 2] 3. Select the true statement about the worst-case time for operations on heaps. A. Niether insertion nor removal is better than linear. B. Insertion is better than linear, but removal is not. C. Removal is better than linear, but insertion is not. D. Both insertion and removal are better than linear. 4. Suppose that we have implemented a priority queue by storing the items in a heap (using an array for the heap items). We are now executing a reheapification upward and the out-of-place node is at data[i] with priority given by data[i].priority. Which of the following boolean expressions is TRUE to indicate that the reheapification IS NOT YET DONE. A. (i > 0) B. (data[(i-1)/2].priority < data[i].priority) C. (i > 0) && (data[(i-1)/2].priority < data[i].priority) D. (i > 0) || (data[(i-1)/2].priority < data[i].priority) 4. Suppose that we have implemented a priority queue by storing the items in a heap. We are now executing a reheapification downward and the out-of-place node has priority of 42. The node's parent has a priority of 72, the left child has priority 52 and the node's right child has priority 62. Which statement best describes the status of the reheapification. A. The reheapification is done. B. The next step will interchange the two children of the out-of-place node. C. The next step will swap the out-of-place node with its parent. D. The next step will swap the out-of-place node with its left child. E. The next step will swap the out-of-place node with its right child. 5. Which formula is the best approximation for the depth of a heap with n nodes? A. log (base 2) of n B> The number of digits in n (base 10) C. The square root of n D. n E. The square of n 6. Which statement is true for a B-tree? A. All entries of a node are greater than or equal to the entries in the node's children. B. All leaves are at the exact same depth. C. All nodes contain the exact same number of entres. D. All non-leaf nodes have the exact same number of children. 7. Suppose that a non-leaf node in a B-tree has 41 entries. How many children will this node have? A. 2 B. 40 C. 41 D. 42 e. 82 8. Suppose that a B-tree has MAXIMUM of 10 and that a node already contains the integers 1 through 10. If a new value, 11, is added to this node, the node will split into two pieces. What values will be in these two pieces? A. The first piece will have only 1 and the second piece will have the rest of the numbers. B. The first piece will have 1 through 5 and the second piece will have 6 through 11. C. The first piece will have 1 through 5 and the second piece will have 7 through 11. D. The first piece will have 1 through 6 and the second piece will have 7 through 11. E. The first piece will have 1 through 10 and the second piece will have only 11. 9. Suppose that X is a B-tree leaf containing 41 entries and having at least one sibling. Which statement is true? A. Any sibling of X is also a leaf. B. Any sibling of X contains at least 41 entries. C. The parent of X has exactly 42 entries. D. X has at least 41 siblings. 10. Suppose you run a O(log n) algorithm with an input size of 1000 and the algorithm requires 110 operations. When you double the input size to 2000, the algorithm now requires 120 operations. What is your best guess for the number of operations required when you again double the input size to 4000? A. 130 B. 140 C. 150 D. 160 E. 170 11. Tree algorithms typically run in time O(d) . What is d? A. The depth of the tree. B. The number of divisions at each level. C. The number of entries in each node. D. The number of nodes in the tree. E. The total number of entries in all the nodes of the tree. SORTING 1. Here is an array of ten integers: 5 3 8 9 1 7 0 2 6 4 Draw this array after the FIRST iteration of the large loop in a selection sort (sorting from smallest to largest). 2. Here is an array of ten integers: 5 3 8 9 1 7 0 2 6 4 Draw this array after the FIRST iteration of the large loop in an insertion sort (sorting from smallest to largest). This iteration has shifted at least one item in the array! 3. Suppose that you are writing a program that has this selectionsort static method available: void selectionsort(int[ ] data, int first, int n); Your program also has an integer array called x, with 10 elements. Write two method activations: The first activation uses selectionsort to sort all of x; the second call uses selectionsort to sort x[3]..x[9]. 4. Describe a case where quicksort will result in quadratic behavior. 5. Here is an array which has just been partitioned by the first step of quicksort: 3, 0, 2, 4, 5, 8, 7, 6, 9 Which of these elements could be the pivot? (There may be more than one possibility!) 6. Give a concise accurate description of a good way for quicksort to choose a pivot element. Your approach should be better than "use the entry at location [0]". 7. Give a concise accurate description of a good way for quicksort to improve its performance by using insertionsort. 8. Here is an array of ten integers: 5 3 8 9 1 7 0 2 6 4 Suppose we partition this array using quicksort's partition function and using 5 for the pivot. Draw the resulting array after the partition finishes. 9. Here is an array of ten integers: 5 3 8 9 1 7 0 2 6 4 Draw this array after the TWO recursive calls of merge sort are completed, and before the final merge step has occured. 10. Implement the following static method: private static void merge(int[ ] data, int first, int n1, int n2); // Precondition: data has at least n1+n2 components starting at // data[first]. The first n1 elements (from data[first] to // data[first+n1-1]) are sorted from smallest to largest, and the last // n2 elements (from data[first+n1] to data[first+n1+n2-1]) are also // sorted from smallest to largest. // Postcondition: Starting at data[first, n1+n2 elements of data have been // rearranged to be sorted from smallest to largest. 11. Write two or three clear sentences to describe how a heapsort works. 12. Fill in the following table for the times to sort an array of n items. Use only big-O notation, and do not have any extraneous constants in your expressions. Worst Average Case Case Binary search of a sorted array . . Insertion sort . . Merge sort . . Quick sort without "median of three" pivot . . selection Quick sort with "median of three" pivot selection . . Selection sort . . Heap sort . . 13. (This question may not have been covered in your class.) Suppose that you implement quicksort nonrecursively using a stack, as in your last programming assignment. You use your algorithm to sort an array of 100 items, and at the start of the final iteration of the while loop, the stack contains just two numbers: 10 (on top) and 90 (on bottom). Write one or two clear sentences to describe which parts of the array are sorted at this point, and which parts of the array remain to be sorted. Multiple Choice 1. In a selection sort of n elements, how many times is the swap function called in the complete execution of the algorithm? A. 1 B. n - 1 C. n log n D. n² 2. Selection sort and quick sort both fall into the same category of sorting algorithms. What is this category? A. O(n log n) sorts B. Divide-and-conquer sorts C. Interchange sorts D. Average time is quadratic. 3. Suppose that a selection sort of 100 items has completed 42 iterations of the main loop. How many items are now guaranteed to be in their final spot (never to be moved again)? A. 21 B. 41 C. 42 D. 43 4. Suppose we are sorting an array of ten integers using a some quadratic sorting algorithm. After four iterations of the algorithm's main loop, the array elements are ordered as shown here: 1 2 3 4 5 0 6 7 8 9 Which statement is correct? (Note: Our selectionsort picks largest items first.) A. The algorithm might be either selectionsort or insertionsort. B. The algorithm might be selectionsort, but could not be insertionsort. C. The algorithm might be insertionsort, but could not be selectionsort. D. The algorithm is neither selectionsort nor insertionsort. 5. Suppose we are sorting an array of eight integers using a some quadratic sorting algorithm. After four iterations of the algorithm's main loop, the array elements are ordered as shown here: 2 4 5 7 8 1 3 6 6. Which statement is correct? (Note: Our selectionsort picks largest items first.) A. The algorithm might be either selectionsort or insertionsort. B. The algorithm might be selectionsort, but it is not insertionsort. C. The algorithm is not selectionsort, but it might be insertionsort. D. The algorithm is neither selectionsort nor insertionsort. 7. When is insertionsort a good choice for sorting an array? A. Each component of the array requires a large amount of memory. B. Each component of the array requires a small amount of memory. C. The array has only a few items out of place. D. The processor speed is fast. 8. What is the worst-case time for mergesort to sort an array of n elements? A. O(log n) B. O(n) C. O(n log n) D. O(n²) 9. What is the worst-case time for quicksort to sort an array of n elements? A. O(log n) B. O(n) C. O(n log n) D. O(n²) 10. Mergesort makes two recursive calls. Which statement is true after these recursive calls finish, but before the merge step? A. The array elements form a heap. B. Elements in each half of the array are sorted amongst themselves. C. Elements in the first half of the array are less than or equal to elements in the second half of the array. D. None of the above. 11. Suppose we are sorting an array of eight integers using quicksort, and we have just finished the first partitioning with the array looking like this: 2 5 1 7 9 12 11 10 Which statement is correct? A. The pivot could be either the 7 or the 9. B. The pivot could be the 7, but it is not the 9. C. The pivot is not the 7, but it could be the 9. D. Neither the 7 nor the 9 is the pivot. 12. What is the worst-case time for heapsort to sort an array of n elements? A. O(log n) B. O(n) C. O(n log n) D. O(n²) 13. Suppose we are sorting an array of eight integers using heapsort, and we have just finished one of the reheapifications downward. The array now looks like this: 6 4 5 1 2 7 8 How many reheapifications downward have been performed so far? A. 1 B. 2 C. 3 or 4 D. 5 or 6 EXAM QUESTIONS 1. How many of the trees in the margin are complete binary trees? A. None B. Two C. Three D. All 2. How many of the trees in the margin are full binary trees? A. None B. Two C. Three D. All 3. What is the maximum number of leaves for a binary tree with 15 nodes? A. Less than 8 B. 8 C. 9 D. 10 E. More than 10 4. Consider a complete binary tree with 1000 nodes, with the data stored in the elements a[0]..a[999] of an array. Where are the parent and the left child of the node stored at a[100]? A. Parent at 49, left child at 200 B. Parent at 49, left child at 201 C. Parent at 50, left child at 200 D. Parent at 50, left child at 201 E. None of the above 5. I am going to execute this code: Stack<int> s; s.push(1); s.push(2); s.push(3); cout << s.pop( ); A. Suppose that s is represented by a partially filled array. Draw the state of the private member variables of s after the above code: _______ __________________________________ used| | data| | | | | | |_______| |______|______|______|______|______| [0] [1] [2] [3] [4] B. Suppose that s is represented by a linked list. Draw the linked list after the above code: _______ head_ptr| | |_______| 6. I am going to execute this code: Queue<int> q; q.insert(1); q.insert(2); q.insert(3); q.insert(4); q.insert(5); cout << q.get_front( ); cout << q.get_front( ); q.insert(6); A. Suppose that q is represented by a partially filled array with a CAPACITY of 5. Draw the state of the private member variables of q after the above code: _______ __________________________________ front| | data| | | | | | |_______| |______|______|______|______|______| [0] [1] [2] [3] [4] _______ rear | | |_______| B. Suppose that q is represented by a linked list. Draw the linked list after the above code: _______ _______ head_ptr| | | |rear_ptr |_______| |_______| 7. Implement the following function. You may use the Stack template class and the Stack operations of push, pop, peek, is_empty, and size. You may also use cin.peek( ) and use "cin >> i" to read an integer. 8. Suppose that you want to implement the PriorityQueue so that insertions occur in constant time, but get_front requires linear time. You will use these class definitions: class PriorityQueue { typedef double Item; ... private: Node *head_ptr; }; struct Node { PriorityQueue::Item data; unsigned int priority; Node *link; }; A. Write the PriorityQueue's insert member function: B. This question continues from the previous page. Write a description of the linear time get_front member function. Use drawings to show a typical example of how get_front will work when the PriorityQueue has five items with priorities 1, 10, 3, 10, and 6. 9. Write a recursive function that has one parameter which is a size_t value called x. The function prints x asterisks, followed by x exclamation points. 10. Implement the following function. Do not use any local variables or loops. void pattern(unsigned int n) // Precondition: n > 0; // Postcondition: The output consists of lines of integers. The first line // is the number n. The next line is the number 2n. The next line is // the number 4n, and so on until you reach a number that is larger than // 4242. This list of numbers is then repeated backward until you get back // to n. Example output with n = 840: 840 1680 3360 6720 6720 3360 1680 840 11. This question will help identify the A+ students. If you don't solve this problem, then don't worry, but do think about the problem after class. This question involves a game with teddy bears. The game starts when I give you some bears. You can then give back some bears, but each time that you give back some bears you must give back half of all your bears. (If you have n bears, and n is even, then you will give back n/2. If n is odd, then you may round down to give back (n-1)/2 bears, or you may round up to give back (n+1)/2 bears.) The goal of the game is to end up with EXACTLY 42 bears. For example, suppose that you start with 337 bears. Then you could make these moves: Start with 337 bears. Give back 168 (which is half of 337, rounding down) to leave 169 bears. You now have 169 bears. Give back 85 (which is half of 169, rounding up) to leave 84 bears. You now have 84 bears. Give back 42 (which is half of 42), to leave 42 bears. You have reached the goal! Write a recursive function to meet this specification: bool bears(int n) // Postcondition: A true return value means that it is possible to win // the bear game by starting with n bears. A false return value means that // it is not possible to win the bear game by starting with n bears. // Examples: // bear(337) is true (as shown above) // bear(42) is true // bear(83), bear(84) and bear(85) are all true // bear(52) is false // bear(41) is false { // Hint: To test whether n is even, use the expression ((n % 2) == 0). Write a declaration of a struct that could be used to store the data from a node in a tree, where each node has integer data and each node can have zero to 1000 children. Write the complete declaration in an exact form that will compile correctly. Do not omit any part of the declaration. 12. Here is a complete binary tree. How would the values of these nodes be stored in an array, using the usual technique for storing a complete binary tree in an array? Draw your array below the tree. _______ | 8 | |_______| ______/ \__________ _______/ \_______ | 4 | | 10 | |_______| |_______| / \ / _______ / \_______ _______/ | 2 | | 6 | | 9 | |_______| |_______| |_______| Here is a binary tree. _______ | 8 | |_______| ______/ \__________ _______/ \_______ | 4 | | 10 | |_______| |_______| / \ / _______ / \_______ _______/ | 2 | | 6 | | 9 | |_______| |_______| |_______| A. In what order would the nodes of this tree be processed for an in-order traversal? B. In what order would the nodes of this tree be processed for a pre-order traversal? C. In what order would the nodes of this tree be processed for a post-order traversal? Concept Map: Course Contents: UNIT I 1. Introduction o 1.1 Some Definitions 1.1.1 Four Fundamental Data Structures o 1.2 Complexity of Algorithms 1.2.1 Big Oh Notation 1.2.2 Examples 1.2.3 An Example: Complexity of Mergesort 1.2.4 Role of the Constant 1.2.5 Worst Case, Average Case, and Amortized Complexity 1.2.6 Big Omega and Big Theta Notations 1.2.7 An Example: o 1.3 To Probe Further o 1.4 Problems 2. Lists o 2.1 List Abstract Data Type 2.1.1 A Program with List ADT o 2.2 Implementation of Lists 2.2.1 Array Implementation of Lists 2.2.2 Pointer Implementation of Lists 2.2.3 Doubly Linked List Implementation o 2.3 Stacks o 2.4 Queues 2.4.1 Pointer Implementation 2.4.2 Circular Array Implementation 2.4.3 Circular Linked List Implementation o 2.5 To Probe Further o 2.6 Problems UNIT II 3. Dictionaries o 3.1 Sets o 3.2 Dictionaries o 3.3 Hash Tables 3.3.1 Open Hashing o 3.4 Closed Hashing 3.4.1 Rehashing Methods 3.4.2 An Example: 3.4.3 Another Example: o 3.5 Hashing Functions 3.5.1 Division Method 3.5.2 Multiplication Method 3.5.3 Universal Hashing o 3.7 Hash Table Restructuring o 3.8 Skip Lists 3.8.1 Initialization: o 3.10 To Probe Further o 3.11 Problems UNIT III 6. Priority Queues o 6.1 Binary Heaps 6.1.1 Implementation of Insert and Deletemin 6.1.2 Creating Heap o 6.2 Binomial Queues 6.2.1 Binomial Queue Operations 6.2.2 Binomial Amortized Analysis 6.2.3 Lazy Binomial Queues o 6.3 To Probe Further o 6.4 Problems 4. Binary Trees o 4.1 Introduction 4.1.1 Definitions 4.1.2 Preorder, Inorder, Postorder 4.1.3 The Tree ADT 4.1.4 Data Structures for Tree Representation o 4.2 Binary Trees o 4.4 Binary Search Tree 4.4.1 Average Case Analysis of BST Operations o 4.7 To Probe Further o 4.8 Problems 4.8.1 General Trees 4.8.2 Binary Search Trees UNIT IV 5. Balanced Trees o 5.1 AVL Trees 5.1.1 Maximum Height of an AVL Tree 5.1.2 AVL Trees: Insertions and Deletions o 5.2 Splay Trees 4.5.1 Search, Insert, Delete in Bottom-up Splaying o 5.2 Red-Black Trees 5.2.1 Height of a Red-Black Tree 5.2.2 Red-Black Trees: Insertions 5.2.3 Red-Black Trees: Deletion o 5.3 2-3 Trees 5.3.1 2-3 Trees: Insertion 5.3.2 2-3 Trees: Deletion o 5.4 B-Trees 5.4.1 Definition of B-Trees 5.4.2 Complexity of B-tree Operations 5.4.3 B-Trees: Insertion 5.4.4 B-Trees: Deletion 5.4.5 Variants of B-Trees o 5.5 To Probe Further o 5.6 Problems 5.6.1 AVL Trees 5.6.2 Red-Black Trees 5.6.3 2-3 Trees and B-Trees UNIT V 9. Sorting Methods o 9.1 Bubble Sort o 9.2 Insertion Sort o 9.3 Selection Sort o 9.4 Shellsort o 9.5 Heap Sort o 9.6 Quick Sort o 9.9 Radix Sorting o 9.10 Merge Sort o 9.11 To Probe Further o 9.12 Problems 11. References and Resources o 11.1 Primary Sources for this Lecture Notes o 11.2 Useful Books o 11.3 Original Research Papers and Survey Articles o 11.4 Web Resources About this document ... Module Level Learning Objectives:

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posted: | 5/13/2011 |

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