14. Longest Common Prefix

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

pay attention to the i = 1!!!!!!!!!!!

if no using res to record, it will return 0;

the bad example

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