leetcode -- 最长公共前缀

class Solution:
    #最长公共前缀
    def longestCommonPrefix(self, strs: List[str]) -> str:
        a = ""
        if not strs:
            return ''
        for i in range(len(strs[0])):
            for j in range(1,len(strs)):
                if i >= len(strs[j]) or strs[j][i] != strs[0][i] :
                    return a
            a=a+strs[0][i]
        return a