LeetCode 172: Factorial Trailing Zeroes

求阶乘末尾0的个数：即为找出2和5的个数。显然2的个数一定比5多，找出5的个数就行了。

class Solution {
public:
    int trailingZeroes(int n) {
        int a=0;
        while(n)
        {
            a+=n/5;
            n/=5;
        }
	    return a;
    }
};