LeetCode | Longest Common Prefix

题目：

Write a function to find the longest common prefix string amongst an array of strings.

思路：

首先找出所有字符串的最小长度。然后依次比较前几位在各个字符串中是否相同，若相同，则作为输出结果；否则，停止循环。

代码：

class Solution {public:    string longestCommonPrefix(vector<string> &strs) {        // Start typing your C/C++ solution below        // DO NOT write int main() function        int len = INT_MAX;        for(int i = 0; i < strs.size(); i++)        {            if(strs[i].size() < len)            {                len = strs[i].size();            }        }                if(len == INT_MAX)        {            len = 0;        }                bool same = true;        int i = 0;        for(; i < len; i++)        {            char c = strs[0][i];            for(int j = 1; j < strs.size(); j++)            {                if(c != strs[j][i])                {                    same = false;                    break;                }            }            if(!same)            {                break;            }        }                int num;        if(!same)        {            num = i;        }        else        {            num = len;        }                string str;        for(int k = 0; k < num; k++)        {            str.push_back(strs[0][k]);        }        return str;    }};