[leecode] Longest Common Prefix

From : https://leetcode.com/problems/longest-common-prefix/

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

class Solution {public:    string longestCommonPrefix(vector<string>& strs) {        if(strs.size() == 0) return "";        string s = "";        int len = strs.size(), flag;        for(int i=0; i<strs[0].length(); i++) {            char c = strs[0][i];            flag = 1;            for(int j=1; j<len; j++) {                char x = strs[j][i];                if(x != c) {flag=0;break; }            }            if(flag) {s += c;} else break;        }        return s;    }};