寻找一个字符串数组中的最长公共子串

class Solution(object):
    def longestCommonPrefix(self, strs):
        """
        :type strs: List[str]
        :rtype: str
        """

        if not strs:
            return ''

        #获取最短和最长的str
        s1 = min(strs)
        s2 = max(strs)

        for i, c in enumerate(s1):
            #不同，截至i
            if c != s2[i]:
                return s1[:i]

        return s1