Number of combinations (N choose R) in C++

Question

Here I try to write a program in C++ to find NCR. But I\'ve got a problem in the result. It is not correct. Can you help me find what the mistake is in the program?

Answer 1

Recursive function is used incorrectly here. fact() function should be changed into this:

int fact(int n){
if(n==0||n==1) //factorial of both 0 and 1 is 1. Base case.
{
    return 1;
}else

    return (n*fact(n-1));//recursive call.

};

Recursive call should be made in else part.

NCR() function should be changed into this:

int NCR(int n,int r){
    if(n==r) {
        return 1;
    } else if (r==0&&n!=0) {
        return 1;
    } else if(r==1)
    {
        return n;
    }
    else
    {
        return fact(n)/(fact(r)*fact(n-r));
    }
};