反转字符串

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

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 s 的形式给出

• 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

示例 1

输入：s = ["h","e","l","l","o"]
输出：["o","l","l","e","h"]

示例 2

输入：s = ["H","a","n","n","a","h"]
输出：["h","a","n","n","a","H"]

提示

• 1 <= s.length <= $10^5$
• s[i] 都是 ASCII 码表中的可打印字符

Typescript 版算法实现

1 ) 方案1：双指针

/**
 Do not return anything, modify s in-place instead.
 */
function reverseString(s: string[]): void {
    let left = 0
    let right = s.length - 1
    while (left <= right) {
        let tmp = s[left]
        s[left] = s[right]
        s[right] = tmp
        left++
        right--
    }
};

2 ) 方案2: 双指针优化

function reverseString(s: string[]): void {
    const n = s.length;
    for (let left = 0, right = n - 1; left < right; ++left, --right) {
        [s[left], s[right]] = [s[right], s[left]];
    }
};