Programming Logic and Design

Question

1. The following module uses a loop. Rewrite it as a recursive module that performs the same operation.

Module trafficSign(int n)

While n > 0

Display "No Parking"

Set n = n - 1

End While

End Module

2. Recursive Array Sum

Design a function that accepts an Integer array and the size of the array as arguments. The function should recursively calculate the sum of all the numbers in the array and return that value.

Answer 1

using namespace std;

#include <iostream>

/*-------------------

Problem in the GIVEN algorithm...

input parameter n MUST be positive,

or else infinite loop

-------------------------------------*/

void trafficSign(int n)

{

if (n<=0) { n = -n; }

while (n > 0 )

{

cout << "No Parking" << endl;

n = n - 1 ;

}

}

//recursive version of the function is capitalized

void TrafficSign(int n)

{

if (n>0)

{

cout << "No Parking" << endl;

trafficSign(n-1);

}

}

long Sum(int * A, int n)

{

if (n>0)

{

return( A[n-1] + Sum(A,n-1));

}

else

{

return(0);

}

}

/****

For example, under this defintion for index parameter n.....

Sum(5) = A[4] + Sum(4)

= A[4] + A[3] + sum(3)

= A[4]+ A[3] + A[2] + Sum(2)

= A[4] + A[3] + A[2] + A[1] + Sum(1)

= A[4] + A[3] + A[2] + A[1] + A[0] + sum(0)

= A[4] + A[3] + A[2] + A[1] + A[0] + 0

**************/

int main()

{

int n=10;

trafficSign(n);

cout <<"------------------------" << endl;

TrafficSign(n);

cout << "-----------------------" << endl;

int A[] = {2,3,4,6,8,12,16,18}; //current total is 69

cout << Sum(A,8);

}