leetcode 14. Longest Common Prefix

 1 string longestCommonPrefix(vector<string> &strs) 
 2     {
 3         string max_prefix = "";
 4         
 5         if (strs.size() <= 0)
 6             return max_prefix;
 7         for (int j = 0; j < strs[0].size(); j++)
 8         {
 9             for (int i = 1; i < strs.size(); i++)
10             {
11                 if ((strs[i].size() <= j) || (strs[0][j] != strs[i][j]))
12                     return max_prefix;
13             }
14             max_prefix += strs[0][j];
15         }
16         
17         return max_prefix;
18     }