Binomial theorem in c++

binomial.cpp

/*
Created By Ariful Islam
Batch E-64 (DIU)
Roll: 34
*/

#include<iostream>
#include <math.h>

using namespace std;

int factorial(int a)
{
    if(a<=1)
    {
        return 1;
    }

    else
    {
        return a*factorial(a-1);
    }

}

int nCr(int p, int q)
{
    return factorial(p)/(factorial(p-q)*factorial(q));
}

int main()
{
    int x,y,n,r;
    double sum=0, temp=0;
    cout<<"Give the value of X\n";
    cin>>x;
    cout<<"Give the value of Y\n";
    cin>>y;
    cout<<"Give the value of N\n";
    cin>>n;

    sum=pow(x,n);

    r=1;
    for(r=1; r<=n; r++) {
        temp=(nCr(n, r))*(pow(x, (n-r)))*(pow(y, r));
        sum=sum+temp;
    }

//    sum=sum+pow(y,n);

    cout<<"Result : "<<sum;

    return 0;
}