package com.x.xyz;

public class HelloWorld {

	public static void main(String[] args) {
		System.out.println("Star !");
		System.out.println(trailingZeroes(0));
		System.out.println(trailingZeroes(1));
		System.out.println(trailingZeroes(2));
		System.out.println(trailingZeroes(3));
		System.out.println(trailingZeroes(4));
		System.out.println(trailingZeroes(5));
		System.out.println(trailingZeroes(6));
		System.out.println(trailingZeroes(7));
	}
	
	public static int trailingZeroes(int n) {
		int sum = 10;
//		if(0 == n) {
//			return 1;
//		}
//		for(int i=1; i<n; i++) {
//			sum = sum * 10;
//		}
//		return sum;
		if(0 == n) {
			return 1 * sum;
		}else{
			return trailingZeroes(n-1) * sum;
		}
	}
}

Factorial Trailing Zeroes , 172题，可能是我没读清楚，还报错。