[BOJ] 백준 2004 조합 0의 개수

[문제]

https://www.acmicpc.net/problem/2004

 

 

[소스 코드]

import java.io.*;
import java.util.*;
public class Main {
	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer st = new StringTokenizer(br.readLine());
		long n = Long.parseLong(st.nextToken());
		long m = Long.parseLong(st.nextToken());
		int two  = cnt(n,2) - (cnt(m,2) + cnt(n-m,2));
		int five = cnt(n,5) - (cnt(m,5) + cnt(n-m,5));
		int result = Math.min(two,five);
		System.out.println(result);
	}  
	private static int cnt(long num,int p) {
		int numCnt = 0;
		while(num/p>0) {
			numCnt += num / p;
			num /= p;
		}
		return numCnt;
	}
}