class Solution {
public:
    /**
     * 
     * @param strs string字符串vector 
     * @return string字符串
     */
    string longestCommonPrefix(vector<string>& strs) {
        // write code here
        int m = strs.size();
        if(m == 0){
            return "";
        }
        if(m == 1){
            return strs[0];
        }
        string res = "";
        int j = 0;
        while(j < strs[0].length()){
            int flag = 1;
            for(int i=1; i<m; i++){
                if(j >= strs[i].length() || strs[i][j] != strs[i-1][j]){
                    flag = 0;
                    break;
                }
            }
            if(flag){
                res.push_back(strs[0][j]);
            }
            j++;
        }
        return res;
        
    }
};