14. Longest Common Prefix

通过i，j将vector变为一个二维数组，先扫每个string的i个字符，再一个字符的遍历

class Solution {public:    string longestCommonPrefix(vector<string>& strs) {        if(strs.empty()) return "";        string max="";        for(int i=0;i<strs[0].size();i++){            char c=strs[0][i];            for(int j=1;j<strs.size();j++)            {                if(i>strs[j].size()-1||c!=strs[j][i])                    return max;            }            max.push_back(c);        }        return max;    }};

class Solution {public:    string longestCommonPrefix(vector<string>& strs) {        if (strs.empty()) return "";        for (int j = 0; j < strs[0].size(); ++j) {            for (int i = 0; i < strs.size() - 1; ++i) {                if (j >= strs[i].size() || j >= strs[i + 1].size() || strs[i][j] != strs[i + 1][j]) {                    return strs[i].substr(0, j);                }            }        }        return strs[0];    }};