Reverse String(Python)

Problem: Write a function that reverses a string. The input string is given as an array of characters char[].
Do not allocate extra space for another array, you must do this by modifying the input array in-place with O(1) extra memory.
You may assume all the characters consist of printable ascii characters.
Example 1:
Input: [“h”,“e”,“l”,“l”,“o”] Output: [“o”,“l”,“l”,“e”,“h”] Example 2:
Input: [“H”,“a”,“n”,“n”,“a”,“h”] Output: [“h”,“a”,“n”,“n”,“a”,“H”]
Resourse:LeetCode Link:https://leetcode-cn.com/problems/reverse-string
Analyse:Swap adjacent But Time Limit Exceeded
Code:

class Solution(object):
    def reverseString(self, s):
        """
        :type s: List[str]
        :rtype: None Do not return anything, modify s in-place instead.
        """
        if len(s)==0:
            return []
        i=len(s)-1
        while(i):  
            j=0
            s.append(s[0])
            while(j