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On this page
  • 1. Link
  • 2. 题目描述
  • 输入
  • 返回值
  • 3. 思路
  • 4. Coding

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  1. DataStructure
  2. String

Reverse String

Easy; String;

PreviousStringNext最长不含重复字符的子字符串

Last updated 6 months ago

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1. Link

2. 题目描述

写出一个程序,接受一个字符串,然后输出该字符串反转后的字符串。(字符串长度不超过1000)示例1

输入

复制

"abcd"

返回值

复制

"dcba"

3. 思路

  1. 因为String在python是immutable 不可变,每次操作都增加新字符串,所以要先把它变成list

  2. 在list中,用two pointers/左右pointers 方法从左右两边进行char的交换,并把 两个pointer向中间移动

  3. 重复步骤2 直到 left >= right 时停止

  4. 返回reverse之后的字符串

  5. Time Complexity: O(n) Space Complexity: O(n) 因为创建了一个list和返回新的字符串

4. Coding

#
# 反转字符串
# @param str string字符串 
# @return string字符串
#
class Solution:
    def solve(self , str ):
        # write code here
        ls = list(str)
        left, right = 0, len(ls)-1
        while left < right:
            ls[left], ls[right] = ls[right], ls[left]
            left += 1
            right -= 1
        return "".join(ls)

反转字符串_牛客题霸_牛客网
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151. 反转字符串中的单词 - 力扣(LeetCode)力扣 LeetCode
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