[백준 - JAVA] 조합

2407번: 조합 (acmicpc.net)

2407번: 조합

http://boj.kr/cfcfe7ea81c9486da13636a1e10cf7f7

공유 소스 보기

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.math.BigInteger;

class Main{
    
    public static void main(String[] args) throws IOException {
		
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
		
		String[] input = br.readLine().split(" ");
		
		BigInteger result = new BigInteger("1"),
				   number;
		
		int[] intArr = {Integer.parseInt(input[0]), Integer.parseInt(input[1])};
		
		for(int i = intArr[0] - intArr[1] + 1; i <= intArr[0]; i++) {
			
			number = new BigInteger(String.valueOf(i));
			result = result.multiply(number);
			
		}
		
		for(int i = 2; i <= intArr[1]; i++) {
			
			number = new BigInteger(String.valueOf(i));
			result = result.divide(number);
			
		}
		
		System.out.println(result);

	}
    
}

 

BigInteger 이용해서

 

조합 구현하였음.