Question

Here are five functions, with descriptions of what they are supposed to do. They are incorrectly implemented. Replace the incorrect implementations of these functions with correct ones that use recursion in a useful way; your solution must not use the keywords while, for, or goto. You must not use global variables or variables declared with the keyword static, and you must not modify the function parameter lists. You must not use any references or pointers as parameters except for the parameters representing arrays.

// Return true if the sum of any combination of elements in the
// array a equals the value of the target.
//
//  Pseudocode Example:

//      comboSum([2, 4, 8], 3, 10) => true

//      comboSum([2, 4, 8], 3, 12) => true

//      comboSum([2, 4, 8], 3, 11) => false

//      comboSum([], 0, 0)         => true
//

bool comboSum(const int a[], int size, int target)
{

    return false;  // This is not always correct.
}

Answer 1

Thanks for the question, here is the implementation of the comboSum() function.

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# include <iostream>

using namespace std;

bool comboSum(const int a[], int size, int target) {

               

                if(size==0) return target==0;

               

                for(int i = size-2; i>=0; i--){

                                if(a[size-1]+a[i] == target){

                                                return true;

                                }

                }

                return comboSum(a,size-1,target);

}

int main(){

               

                int a[] = {2,4,8};

                if(comboSum(a,3,9)) cout<<"true";

                else cout<<"false";

}

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