Number of combinations

topic:

Find the combination of r numbers among n natural numbers (1, 2...n), for example, when n=5, r=3, all combinations are

1 2 3 
1 2 4
1 2 5
1 3 4
1 3 5
1 4 5
2 3 4
2 3 5
2 4 5
3 4 5

This question only requires the number of combinations

Enter description:

5 3

20 18

Output description:

10 

190

#include <iostream>
using namespace std;

int main(){
	int m, i, j, n;
	int M = 1, N = 1;
	
	cin >> m >> n;
	
	if(m - n < n){
		n = m - n;
	}
	for(i = 1; i <= n; i++){
		M = M * m;
		m = m - 1;	
	}
	for(j = 1; j <= n; j++){
		N=N*j;
	}
	cout << M / N;
}