Deck 15: Recursion

Question 1

Look at the following pseudocode algorithm. algorithm Test14(int x)
If (x < 8)
Return (2 * x)
Else
Return (3 * Test14(x - 8)+ 8)
End Test14
What value is returned for Test14(7)?

A) 0
B) 7
C) 14
D) -5

Answer 1

C

Question 2

Look at the following pseudocode algorithm. Algorithm Test3(int a,int b)
If (a < b)
Return 5
Else if ( a == b)
Return -5;
Else
Return (a + Test3(a - 1,b)
End Test3
What is the base case for the algorithm?

A) a < b
B) a == b
C) Both a and b
D) Neither a or b

Answer 2

C

Question 3

Look at the following method. public static int test2(int x,int y)
{
If ( x < y)
{
Return -5;
}
Else
{
Return (test2(x - y,y + 5)+ 6);
}
}
What is the recursive case for the method?

A) x < y
B) -5
C) x >= y
D) x != y

Answer 3

C

Question 4

The depth of recursion is

A) the number of times that a method calls itself.
B) the value returned from the last recursive call.
C) the value that will terminate the recursive calls.
D) There is no such term.

Question 5

Look at the following pseudocode algorithm. algorithm Test14(int x)
If (x < 8)
Return (2 * x)
Else
Return (3 * Test14(x - 8)+ 8)
End Test14
What is the recursive case for the algorithm?

A) x < 8
B) 2 * x
C) x != 8
D) x >= 8

Question 6

Look at the following pseudocode algorithm. algorithm Test14(int x)
If (x < 8)
Return (2 * x)
Else
Return (3 * Test14(x - 8)+ 8)
End Test14
What is the base case for the algorithm?

A) x < 8
B) 2 * x
C) 3 * Test14(x - 8)+ 8
D) x >= 8

Question 7

How many times will the following method call itself,if 10 is passed as the argument? public static void message(int n)
{
If (n > 0)
{
System.out.println("Print this line. \ n");
Message(n + 1);
}
}

A) 1
B) 9
C) 10
D) An infinite number of times

Question 8

Like a loop,a recursive method must have

A) a counter.
B) some way to control the number of times it repeats itself.
C) a return statement.
D) a predetermined number of times it will execute before terminating.

Question 9

A recursive method is a method that

A) uses four-letter words to tell you when you have an error.
B) keeps recurring in your program code.
C) calls itself.
D) is a method that has a loop in it.

Question 10

Look at the following method. public static int test2(int x,int y)
{
If ( x < y)
{
Return -5;
}
Else
{
Return (test2(x - y,y + 5)+ 6);
}
}
What is returned for test2(18,5)?

A) 6
B) -5
C) 7
D) 1

Question 11

The actions that the JVM must perform any time a method is called is called

A) stack frame.
B) overhead.
C) housekeeping.
D) method calls.

Question 12

Look at the following method. public static int test2(int x,int y)
{
If ( x < y)
{
Return -5;
}
Else
{
Return (test2(x - y,y + 5)+ 6);
}
}
What is the depth of test2(18,5)?

A) 0
B) 1
C) 2
D) 3

Question 13

The Towers of Hanoi is

A) a mathematical game
B) often used in computer science textbooks
C) demonstrates the power of recursion
D) All of the above

Question 14

Look at the following method. public static int test2(int x,int y)
{
If ( x < y)
{
Return -5;
}
Else
{
Return (test2(x - y,y + 5)+ 6);
}
}
What is returned for test2(10,20)?

A) 6
B) 10
C) 1
D) -5

Question 15

Look at the following pseudocode algorithm. Algorithm Test3(int a,int b)
If (a < b)
Return 5
Else if ( a == b)
Return -5;
Else
Return (a + Test3(a - 1,b)
End Test3
What is the recursive case for the algorithm?

A) a < b
B) a == b
C) a > b
D) None of the above

Question 16

Look at the following pseudocode algorithm. algorithm Test14(int x)
If (x < 8)
Return (2 * x)
Else
Return (3 * Test14(x - 8)+ 8)
End Test14
What value is returned for Test14(16)?

A) 8
B) 16
C) 24
D) 32

Question 17

Look at the following pseudocode algorithm. algorithm Test14(int x)
If (x < 8)
Return (2 * x)
Else
Return (3 * Test14(x - 8)+ 8)
End Test14
What is the depth of Test14(7)?

A) 0
B) 1
C) 6
D) 7

Question 18

Look at the following pseudocode algorithm. algorithm Test14(int x)
If (x < 8)
Return (2 * x)
Else
Return (3 * Test14(x - 8)+ 8)
End Test14
What is the depth of Test14(16)?

A) 0
B) 1
C) 2
D) 3

Question 19

To solve a program recursively,you need to identify at least one case in which the problem can be solved without recursion - this is known as

A) the recursive case.
B) the terminal case.
C) the base case.
D) the final case.

Question 20

Look at the following method. public static int Test2(int x,int y)
{
If ( x < y)
{
Return -5;
}
Else
{
Return (Test2(x - y,y + 5)+ 6);
}
}
What is the base case for the method?

A) x < y
B) -5
C) Test2(x - y,y + 5)+ 6
D) +6

Question 21

This type of method is a method that calls itself.

A) Looping
B) Circular
C) Recursive
D) Reoccurring

Question 22

Recursive algorithms are usually less efficient than iterative algorithms.

Question 23

Like _________,a recursive method must have some way to control the number of times it repeats.

A) a loop
B) any method
C) a GUI method
D) a rumor

Question 24

A problem can be solved recursively if it can be broken down into successive smaller problems that are unique within the overall problem.

Question 25

The part of a problem that is solved with recursion is known as the

A) terminal case
B) final case
C) re-occurring case
D) recursive case

Question 26

Which of the following problems cannot be programmed recursively?

A) Towers of Hanoi
B) Summing a range of array elements
C) Finding the greatest common divisor
D) All of the above can be programmed recursively

Question 27

If Method A calls Method B which in turn calls Method A,it is called indirect recursion.

Question 28

How many times will the following method call itself,if 10 is passed as the argument? public static void message(int n)
{
If (n < 0)
{
System.out.println("Print this line. \ n");
Message(n + 1);
}
}

A) 0
B) 9
C) 10
D) An infinite number of times

Question 29

Look at the following pseudocode algorithm. Algorithm gcd(x,y)
If (x < y)
Gcd (y,x)
Else
If (y = 0)
Return x
Else
Return gcd(y,x mod y)
End gcd
What is the base case for the algorithm gcd?

A) x < y
B) y == 0
C) x == 0
D) y > x

Question 30

Any problem that can be solved recursively can also be solved iteratively.

Question 31

Look at the following pseudocode algorithm. Algorithm gcd(x,y)
If (x < y)
Gcd (y,x)
Else
If (y = 0)
Return x
Else
Return gcd(y,x mod y)
End gcd
What is returned from gcd(60,24)?

A) 60
B) 24
C) 12
D) 66

Question 32

The number of times that a method calls itself is known as the

A) height of recursion
B) depth of recursion
C) width of recursion
D) length of recursion

Question 33

Indirect recursion occurs when a method calls another method that in turn calls the first method.

Question 34

A problem can be solved recursively if it can be broken down into successive smaller problems that are identical to the overall problem.