87 - 反转字符串

题目

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[] 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。

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：

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

示例 2：

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

解答

既然是原地修改，第一反应是双指针对换

var reverseString = function (s) {
  for (let i = 0, j = s.length - 1; i < Math.floor(s.length / 2); i++ , j--) {
    [s[i], s[j]] = [s[j], s[i]]
  }
};

Runtime: 116 ms, faster than 54.48% of JavaScript online submissions for Reverse String.

Memory Usage: 47.3 MB, less than 11.11% of JavaScript online submissions for Reverse String.

结果一遍成功哈哈哈，感觉自己酷酷的😎

go写法也一样咯

func reverseString(s []byte) {
    for i, j := 0, len(s)-1; i < len(s)/2; i, j = i+1, j-1 {
        s[i], s[j] = s[j], s[i]
    }
}

Runtime: 656 ms, faster than 58.16% of Go online submissions for Reverse String.

Memory Usage: 8.5 MB, less than 100.00% of Go online submissions for Reverse String.

感觉速度比js慢很多啊，很可能是每次互换切片元素，都要重新建一个新的切片。。

猜测js对此进行过了优化

直接翻转啊

看了题解发现，还是想复杂了哈哈😂

var reverseString = function (s) {
  s.reverse()
};

Runtime: 104 ms, faster than 93.94% of JavaScript online submissions for Reverse String.

Memory Usage: 46.6 MB, less than 95.56% of JavaScript online submissions for Reverse String.

go没有这种方便的函数，手写一个的话那就和方法一差不多了