[C++] 백준 11050번 : 이항 계수 1

https://www.acmicpc.net/problem/11050

#include <iostream>

using namespace std;

int main() {

int N,K;

cin >> N >> K;

int r1 = 1,r2=1,r3=1;

for (int i = 1; i <= N; i++) 

r1 = r1 * i;

for (int i = 1; i <= K; i++) 

r2 = r2 * i;

for (int i = 1; i <= N-K; i++) 

r3 = r3 * i;

cout << r1 / (r2*r3);

}