面试题-python3 查找字符串数组中的最长公共前缀

"""
编写一个函数来查找字符串数组中的最长公共前缀。如果不存在公共前缀，返回空字符串 ""
输入: ["flower","flow","flight"]
输出: "fl"
输入: ["dog","racecar","car"]输出: ""
解释: 输入列表不存在公共前缀，返回""。
"""
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def get_common_str(list_a):
    '''输入列表a，返回公共子串
    输入: ["flower","flow","flight"]
    输出: "fl"
    输入: ["dog","racecar","car"]输出: ""
    '''
    if len(list_a) == 0:
        return ''
    common_str = ''  # 公共字符串

    # 先找出最短的字符串
    min_str = min(list_a, key=lambda x: len(x))
    # print(min_str)  # 最短的字符串flow
    for i in range(len(min_str)):
        flag = False  # 退出外部循环标志
        for j in list_a:
            if min_str[i] != j[i]:
                common_str = min_str[:i]
                flag = True
                break
        if flag:
            break

    return common_str

if __name__ == '__main__':
    a = ["flower", "flow", "flight"]
    print(get_common_str(a))
    b = ["dog", "racecar", "car"]
    print(get_common_str(b))