Longest common prefix (Python)

Write a function to find the longest common prefix string array.

If there is no common prefix, it returns an empty string "."

Example 1:

Input: [ "flower", "flow ", "flight"]
Output: "fl"
Example 2:

Input: [ "dog", "racecar ", "car"]
Output: ""
Explanation: there is no input common prefix.
Description:

All input contains only lowercase letters az.

Source: stay button (LeetCode)
link: https: //leetcode-cn.com/problems/longest-common-prefix
I did the title of the most wanted to start with the first character to match all strings, found a flaw :

When a character string length than the first and smaller matching error will occur, so the minimum point is determined as the length of the list.

Solution class: 
    DEF longestCommonPrefix (Self, strs): 
        IF len (strs) == 1: # Only a return array of strings itself. 
            STRs return [0] 
        if len (STRs) == "" or STRs == []: 
            return "" 
        A = len (STRs) 
        n-A =. 1- 
        the while n-> = 0: # descending order 
            if len ( STRs [n-]) <len (STRs [n--. 1]): 
                S = STRs [n-] 
                STRs [n-] = STRs [n--. 1] 
                STRs [n--. 1] = S 
            n-- =. 1 
        B = len (STRs [len (strs) -1]) # obtain a minimum length of string length, and to ensure that the last array of strings shortest 
        J = 0 
        P = 0 
        iF B <= 0: # 0 when a length equal to the minimum, so there is no common prefix. 
            return "" 
        the while True:
            STRs the while [0] [J] = STRs [P +. 1] [J]:!   
                IF STRs [0] [: J] == None: 
                    return "" 
                the else: 
                    return STRs [0] [: J] 
            P = + . 1 
            iF P> =. 1-a: 
                j =. 1 + 
                P = 0 
                iF j == len (STRs [-P. 1]): # when j is equal to the shortest length of the string returned directly 
                    return strs [0] [: j ]