[LintCode] 尾部的零

class Solution {
 public:
    // param n : description of n
    // return: description of return 
    long long trailingZeros(long long n) {
        long long counts = 0;
        for(long long i = 5; n / i; i *= 5)
            counts += n / i;
        return counts;
    }
};