344. Reverse String

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”]

思路

题意来讲就是在字符数组中原地前后交换，这里我也采用了异或来做。

但是严格来讲，在这里用异或是错误的。在工程中不允许出现这样的代码。

推荐一篇文章：用异或来交换两个变量是错误的

• 时间复杂度 O(N)
• 空间复杂度 O(1)

代码

impl Solution { pub fn reverse_string(s: &mut Vec<char>) { let n = s.len(); if n == 0 { return; } for i in 0..n/2 { let j = n -1 -i; s[i] = ((s[i] as u8) ^ (s[j] as u8)) as char; s[j] = ((s[i] as u8) ^ (s[j] as u8)) as char; s[i] = ((s[i] as u8) ^ (s[j] as u8)) as char; } } }

• 执行用时: 28 ms
• 内存消耗: 5.3 MB

题型与相似题

题型

1.字符串
2.双指针

相似题

• 541. Reverse String II
• 345. Reverse Vowels of a String

代码链接

reverse_string