[백준, BOJ 2407] 조합 (java)

https://www.acmicpc.net/problem/2407

2407번: 조합

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문제

$_{n}\mathrm{C}_{m}$을 출력한다.

입력

n과 m이 주어진다. (5 ≤ n ≤ 100, 5 ≤ m ≤ 100, m ≤ n)

출력

$_{n}\mathrm{C}_{m}$을 출력한다.

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예제 입력 1

100 6

예제 출력 1

1192052400

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import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.math.BigInteger;
import java.util.StringTokenizer;

public class Main {
	
	private static BigInteger factorial(int s, int e) {
		
		BigInteger mul = new BigInteger("1");
		
		for (int i = s; i <= e; i++) {
			mul = mul.multiply(new BigInteger(String.valueOf(i)));
		}
		
		return mul;
	}

	public static void main(String[] args) throws Exception {

		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer st = new StringTokenizer(br.readLine());
		int n = Integer.parseInt(st.nextToken());
		int m = Integer.parseInt(st.nextToken());
		
		BigInteger result = factorial(m + 1, n).divide(factorial(1, n - m));
		
		System.out.println(result);
	}

}