Question 1

Give the three criteria for a correct value being returned by a recursive function.

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Question 2

Give a general outline of a successful recursive function definition.

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Question 3

Write a recursive function
double recSum(double array[],int count);
that takes an int argument and returns the sum of count array entries.

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double recSum(double array[],int count);
that...

Question 4

Iterative solutions are always possible.Why then,would we bother with recursive solutions to problems? What advantages do some recursive algorithms have over the iterative versions?

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Question 5

In the binary search,each pass (recursion or iteration)selects a subproblem of the original problem to solve.What fraction of the array sent to an initial call is eliminated in the next iterative pass or recursive call?

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Question 6

In the binary search,if the array being searched has 32 elements in it,how many elements of the array must be examined to be certain that the array does not contain the key? What about 1024 elements? Note: the answer is the same regardless of whether the algorithm is recursive or iterative.

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Question 7

Here is a recursive function.Write an iterative version of it.Hint: Be sure you get the number of copies of "Hip" right.
void rec_cheers(int n)
{
 using namespace std;
 if(1==n)
 cout << "Hurray!" << endl;
 else
 {
 cout << "Hip,";
 rec_cheers(n-1);
}
}

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Question 8

Write a recursive version of this iterative function:
int g(int n)
{
int h = 1;
while (n > 1)
{
h = h * n;
n--;
}
return h;
}

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The answer of Write a recursive version of this iterative...

Question 9

The binary search algorithm in the text makes recursive calls on subarrays of the array passed to the algorithm.The range passed to the search function is first to last.The search algorithm makes recursive calls on the left or right subarray that target will be in,if the target is present.What are the left and right ends of the right subarray?

Accepted Answer

The right subarray, when dividing an array for a binary search, starts just after the midpoint to exclude the already checked middle element. Therefore, the correct range for the right subarray is from mid + 1 to last, making D) mid + 1, last the correct choice.

Question 10

Overloading and recursion look similar.Both situations call functions with the same name.Explain the difference.

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Question 11

Here is an iterative function.Write a recursive function that does the same thing.Be sure you write the correct number of copies of the cheer,"Hip,Hip,Hurray!".For this problem,ignore namespace issues.
void iter_cheers(int n)
{
 for(int i = 0;i < n-1;i++)//this is the tricky part!
cout << "Hip,";
 cout << "Hurray!" << endl;
}

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Question 12

Explain in your own words what recursion means (in connection with definitions of ideas and as a programming technique. )

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Question 13

The binary search algorithm in the text makes recursive on subarrays of the array passed to the algorithm.The range passed to the search function is first to last.The search algorithm makes recursive calls on the left or right subarray that target will be in,if the target is present.What are the left and right ends of the left subarray?

Accepted Answer

In the binary search algorithm, if the middle element is greater than the search target, then we recursively search in the left subarray which ranges from first index to mid-1 index. Therefore, the left end of the left subarray is "first" and the right end of the left subarray is "mid-1". So, option A "first, mid-1" is the correct choice.

Question 14

Here is a recursive function that is supposed to return the factorial.Identify the line(s)with the logical error(s).Hint: This compiles and runs,and it computes something.What is it?
int fact( int n )//a
{
int f = 1;//b
if ( 0 == n || 1 == n )//c
return f;//d
else
{
f = fact(n - 1);//f
f = (n-1)* f;//g
return f;//h
}
}

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Question 15

Describe the stack memory (or data)structure.Give a four-word description of the stack discipline.

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Question 16

Write a recursive void function that has one parameter which is a positive integer.When called,the function is to write its arguments to the screen backward: If the argument is 1234,the output should be.4321.

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Question 17

Give the three criteria for a correct recursive void-function.

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Question 18

Give the recursive binary search algorithm.

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Question 19

In both the iterative and the recursive binary search,explain why the condition for halting the routine with the variable found assigned false is first > last.

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Question 20

How does the computer keep track of all the calls to a recursive function?

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Quiz 13: Recursion