344. Reverse String

题目：反转字符串

Write a function that takes a string as input and returns the string reversed.

Example:
Given s = "hello", return "olleh".

五种解法：

#直接逆序
class Solution(object):
    def reverseString(s):
        return s[::-1]

耗时56ms

#前后对称位互换
class Solution(object):
    def reverseString(s):
        li = list(s)
        l = len(s)
        for i, j in zip(range(len(l)-1, 0, -1), range(l//2)):
             li[i], li[j] = li[j], li[i]
        reurn ''.join(li)

耗时52ms

#递归 逐个逆转
class Solution(object):
    def reverseString(s):
        if len(s) <=1:
            return s
        return self.reverseString(s[1:]) + s[0]

耗时64ms

#使用队列
class Solution(object):
    def reverseString(s):
        from collections import deque
        q = deque()
        q.extendleft(s)
        return ''.join(q)

耗时60ms

#循环逆序
class Solution(object):
    def reverseString(s):
        return ''.join([s[i] for i in range(len(s)-1,-1,-1)])

耗时52ms