Recursion.docx - Student of Fortune

					1. The recur method prints a sequence of digits on a single line.

   public static void recur (int n)
   {
     if(n==1)
     {
       System.out.print(n);
     }
     else
     {
       System.out.print(n);
       recur(n - 1);
     }
   }

   What does the method call recur(5) display?



2. The method factorial returns the product of all integers between 1 and n inclusive.

   For example:
   If n = 10, factorial should return 3628800, since 10! = 10*9*8*7*6*5*4*3*2*1 =
   3628800.

   Write a recursive version of factorial.

   (Remember: it's important to identify a base case for your recursive definition, so that
   your method will terminate properly).

   Public int factorial (int n){

   }//end method



3. The method sumN returns the sum of the integers from 1 to n.

   For example:
   If n = 5, then sumN should return 15, since 5+4+3+2+1 = 15.

   Write a recursive version of sumN.
    (Remember: it's important to identify and include a nonrecursive base case, so that your
    method will terminate properly).

    Public int sumN (int n){
    }//end method

4. The rowPrint method prints a sequence of digits on a single line.

    public static void rowPrint (int n)
    {
      if(n==1)
      {
        System.out.print(n);
      }
      else
      {
       rowPrint(n - 1);
       System.out.print(n);
      }
    }

    What does the method call rowPrint(3) display?



5. public static void recur2(int n)
   {
     if(n<=0)
     {
       return;
     }
     else
     {
       recur2(n - 2);
       System.out.print(n);
     }
   }

    What does the method call recur2(2) display?

    Enter your answer in the answer box below.
6. Here's another recur2 problem. Remember: the recur2 method prints a sequence of digits on
   a single line.

   public static void recur2 (int n)
   {
     if(n<=0)
     {
       return;
     }
     else
     {
       recur2(n - 2);
       System.out.print(n);
     }
   }

   What does the method call recur2(5) display?

7. The method sumEvens returns the sum of the numbers from 1 to n that are even (that is,
   divisible by 2).

   For example:
   If n = 10, sumEvens should return 30, since the numbers from 1 to 10 that are evens are: 2, 4,
   6, 8 and 10.

   Write a recursive version of sumEvens.
   (Remember that it's important to identify the base case so that your method will terminate
   properly).

   Public int sumEvens(int n){
   }//end method

8. The method sumD3 returns the sum of the numbers from 1 to n that are divisible by 3.

   For example:
   If n = 10, sumD3 should return 18, since the numbers from 1 to 10 that are divisible by 3 are: 3,
   6, and 9.

   Write a recursive version of sumD3.
   (Remember that it's important to identify the base case so your method will terminate
   properly).
Public int sumD3(int n){

}//end method

    9. The method sumNSquares calculates the sum of the squares of consecutive integers from 1 to
       n, where n is a positive integer.

        For example:

        If n = 5, sumNSquares should return 55, since
        (1*1) + (2*2) + (3*3) + (4*4) + (5*5) = 55.

        Write a recursive version of sumNSquares. (Remember that it's important to identify the base
        case so that your method will terminate properly).
        public int sumNSquares(int n) {
        } //end method

    10. The method sumNSquaresD3 returns the sum of the squares of consecutive integers from 1 to
        n that are divisible by 3, given that n is a positive integer.

        For example:
        If n = 6, sumNSquaresD3 should return 45, since the squares are:
        (1*1) = 1, (2*2) = 4, (3*3) = 9, (4*4) = 16, (5*5) = 25, (6*6) = 36
        but only 9 and 36 are divisible by 3, and 9 + 36 = 45.

        Write a recursive version of sumNSquaresD3.
        (Remember that it's important to identify the base case so your method will terminate
        properly).

        public int sumNSquaresD3 (int n) {
        } //end method

				
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posted:2/27/2012
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