Longest Common Prefix

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

求最长公共前缀。

代码例如以下：

class Solution {public:    string longestCommonPrefix(vector
     
      & strs) {       	int length = strs.size();		if (length <= 0)			return "";		string prefix = strs[0];		int i, j;		for (i=1; i