LeetCode 344. Reverse String

Easy

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"]

Go Code

使用双索引技术，时间复杂度 O(n/2)。

func reverseString(s []byte)  {
    var length int = len(s)

    if length <= 1 {
        return
    }

    var head int = 0
    var tail int = length-1

    for head < tail {
        s[head], s[tail] = s[tail], s[head]

        head++
        tail--
    }
}