leetcode 14 最长公共前缀

class (object):
    def longestCommonPrefix(self, strs):
        """
        :type strs: List[str]
        :rtype: str
        """
        if not strs:
            return ""
        s1 = max(strs)
        s2 = min(strs)
        for i, s in enumerate(s2):
            if s != s1[i]:
                return s2[:i]
        return s2