programming-examples/c++/Basic/nCr & nPr.cpp

#include < iostream.h >

long factorial(int);
long find_ncr(int, int);
long find_npr(int, int);

main()
{
    int n, r;
    long ncr, npr;
    cout<<"Enter the value of n and r\n";
    cin>>n>>r;
    ncr = find_ncr(n, r);
    npr = find_npr(n, r);
    cout<<n<<"C"<<r<<" ="<<ncr<<"\n";
    cout<<n<<"P"<<r<<"=" <<npr<<"\n";
    return 0;
}

long find_ncr(int n, int r)
{
    long result;
    result = factorial(n)/(factorial(r)*factorial(n-r));
    return result;
}

long find_npr(int n, int r)
{
    long result;
    result = factorial(n)/factorial(n-r);
    return result;
}

long factorial(int n)
{
    int c;
    long result = 1;
    for( c = 1 ; c < = n ; c++ )
        result = result*c;
    return ( result );
}