Question 1

Recursion will take place if any of the following happen:
I method A calls method B, which calls method C
II method A calls method B, which calls method A
III method A calls method A

Accepted Answer

A)  I 
B)  I and II 
C)  II 
D)  II and III

Question 2

Consider the fib method from the textbook shown below: public static long fib(int n)
{
If (n <= 2)
{
Return 1; // line #1
}
Else
{
Return fib(n - 1) + fib(n - 2); // line #2
}
}
Assume line #2 is changed to this:
Else { return 2 * fib(n - 1) + 2 * fib(n - 2); }
What effect will this change have?

Accepted Answer

A)  This will return 5 from fib(4) 
B)  This will return 8 from fib(4) 
C)  This will return 10 from fib(4) 
D)  This will cause an exception on a call fib(4)

Question 3

Consider the recursive square method shown below. It takes a non-negative int argument. Then it recursively adds the number n to itself n times to produce the square of n. Complete the correct code for the square helper method. public int square(int n)
{
____________________;
}
Public int square(int c, int n)
{
If (c == 1)
{
Return n;
}
Else
{
Return n + square(c - 1, n);
}
}

Accepted Answer

A)  return square(n, n) 
B)  return square(n) 
C)  return square(n - 1, n) 
D)  return square(n, n - 1)

Question 4

Consider the helper method reversePrint, which uses recursion to display in reverse the elements in a section of an array limited by the firstIndex and lastIndex arguments. What statement should be used to complete the recursive method? public static void reversePrint(int[] array, int firstIndex, int lastIndex)
{
If (firstIndex < lastIndex)
{
________________________________________
}
System.out.println(array[firstIndex]);
}
Public static void main(String[] args)
{
Int [] numbers = { 4, 7, 1, 0, 2, 7 };
ReversePrint(numbers, 0, numbers.length - 1);
}

Accepted Answer

A)  reversePrint(array, firstIndex, lastIndex + 1); 
B)  reversePrint(array, firstIndex, lastIndex - 1); 
C)  reversePrint(array, firstIndex + 1, lastIndex - 1); 
D)  reversePrint(array, firstIndex + 1, lastIndex);

Question 5

Consider the mutually recursive methods below. Select the method call that could be used to generate the output sequence: A5 B4 A3 B2 A1 public static void methodA(int value)
{
If (value > 0)
{
System.out.print(" A" + value);
MethodB(value - 1);
}
}
Public static void methodB(int value)
{
If (value > 0)
{
System.out.print(" B" + value);
MethodA(value - 1);
}
}

Accepted Answer

A)  methodA(5); 
B)  methodB(5); 
C)  methodA(4); 
D)  methodB(4);

Question 6

Consider the recursive method myPrint in this code snippet: public void myPrint(int n)
{
If (n < 10)
{
System.out.print(n);
}
Else
{
Int m = n % 10;
System.out.print(m);
MyPrint(n / 10);
}
}
What is printed for the call myPrint(821)?

Accepted Answer

A)  821 
B)  128 
C)  12 
D)  10

Question 7

Given the following class code: public class RecurseMore
{
Private static int total;
Public static void main(String[] args)
{
System.out.println(recurse(4));
}
Public static int recurse(int n)
{
Int total = 0;
If (n == 0)
{
Return 0;
}
Else
{
Total = 4 + recurse(n - 2);
}
Return total;
}
}
What values will be printed when this code is executed?

Accepted Answer

A)  0, 4, and 8 
B)  4 and 8 
C)  4 
D)  8

Question 8

Consider the recursive method shown below: public static int strangeCalc(int bottom, int top)
{
If (bottom > top)
{
Return -1;
}
Else if (bottom == top)
{
Return 1;
}
Else
{
Return bottom * strangeCalc(bottom + 1, top);
}
}
What value will be returned with a call to strangeCalc(4,7)?

Accepted Answer

A)  1 
B)  -1 
C)  120 
D)  840

Question 9

Consider the iterative version of the fib method from the textbook shown below: public static long fib(int n)
{
If (n <= 2)
{
Return 1;
}
Long fold = 1;
Long fold2 = 1;
Long fnew = 1;
For (int i = 3; i <= n; i++)
{
Fnew = fold + fold2;
Fold2 = fold;
Fold = fnew;
}
Return fnew;
}
How many iterations of the for loop will there be for the call fib(6)?

Accepted Answer

A)  6 
B)  5 
C)  4 
D)  3

Question 10

If a recursive method does not simplify the computation within the method and the base case is not called, what will be the result?

Accepted Answer

A)  The terminating condition will be executed and recursion will end. 
B)  The recursion calculation will occur correctly regardless. 
C)  This cannot be determined. 
D)  Infinite recursion will occur.

Exam 13: Recursion

Recursion will take place if any of the following happen: I method A calls method B, which calls method C II method A calls method B, which calls method A III method A calls method A

Consider the fib method from the textbook shown below: public static long fib(int n) { If (n <= 2) { Return 1; // line #1 } Else { Return fib(n - 1) + fib(n - 2) ; // line #2 } } Assume line #2 is changed to this: Else { return 2 * fib(n - 1) + 2 * fib(n - 2) ; } What effect will this change have?

Consider the recursive method myPrint in this code snippet: public void myPrint(int n) { If (n < 10) { System.out.print(n) ; } Else { Int m = n % 10; System.out.print(m) ; MyPrint(n / 10) ; } } What is printed for the call myPrint(821) ?

Consider the recursive method shown below: public static int strangeCalc(int bottom, int top) { If (bottom > top) { Return -1; } Else if (bottom == top) { Return 1; } Else { Return bottom * strangeCalc(bottom + 1, top) ; } } What value will be returned with a call to strangeCalc(4,7) ?

If a recursive method does not simplify the computation within the method and the base case is not called, what will be the result?