baekjoon 11050

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Idea

binomial coefficient formula
input --- n, k || ( 1 <= n <= 10, 0 <= k <= n )
n! / (k! (n - k)!)

• Factorial

https://en.wikipedia.org/wiki/

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Code

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>

// binomial coefficient formula
// input --- n, k  || ( 1 <= n <= 10, 0 <= k <= n )
// n! / (k! (n - k)!)

int fact(int n) {
	int result = 1;

	for (int i = 1; i <= n; i++) {
		result *= i;
	}
	
	return result;
}

int main(void) {
	int n, k;

	scanf("%d %d", &n, &k);

	int N = fact(n);
	int K = fact(k);
	int nk = fact(n - k);

	printf("%d", N / (K * nk));
	
	return 0;
}

😎