#
# 
# @param strs string字符串一维数组 
# @return string字符串
#
class Solution:
    def longestCommonPrefix(self, strs):
        if not strs: return ""
        s1 = min(strs)
        s2 = max(strs)
        for i,x in enumerate(s1):
            if x != s2[i]:
                return s2[:i]
        return s1