LeetCode012 : python反转字符串

原题地址：

https://leetcode-cn.com/problems/reverse-string/

题目描述

编写一个函数，其作用是将输入的字符串反转过来。输入字符串以字符数组 

char[]

不要给另外的数组分配额外的空间，你必须原地修改输入数组、使用 O(1) 的额外空间解决这一问题。

你可以假设数组中的所有字符都是 ASCII 码表中的可打印字符。

示例 1：

[code]输入：["h","e","l","l","o"]
输出：["o","l","l","e","h"]

示例 2：

[code]输入：["H","a","n","n","a","h"]
输出：["h","a","n","n","a","H"]

[code]class Solution:
def reverseString(self, s):
"""
:type s: str
:rtype: str
"""
n = len(s)
ret = []
for i in range(n):
ret.append(s[n - i - 1])
return "".join(ret)