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HappyLeetcode39:Factorial Trailing Zeroes

Given an integer n, return the number of trailing zeroes in n!.

Note: Your solution should be in logarithmic time complexity.

 

这个是我的代码,但是超时

class Solution {public:    int trailingZeroes(int n) {        if (n <= 4)            return 0;        int count = 0;        int multi = 1;//计算所需内容累乘的积        for (int i = 5; i <= n; i += 5)        {            multi *= i;            while (multi % 5 == 0)            {                multi /= 5;                count++;            }        }        return count;    }};

 

网上抄的别人的答案

class Solution {
public:
    int trailingZeroes(int n) 
    {
    int c = 0;
    for( ; n > 4; c += (n/=5) );
    return c;
    }
};

class Solution {public:    int trailingZeroes(int n)      {    int c = 0;    for( ; n > 4; c += (n/=5) );    return c;    }};

HappyLeetcode39:Factorial Trailing Zeroes