ReverseString.swift

//
//  ReverseString.swift
//  LeetCode.swift
//
//  Created by 叶帆 on 2020/3/7.
//  Copyright © 2020 Suzhou Coryphaei Information&Technology Co., Ltd. All rights reserved.
//

/**
 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"]
 
 =====
 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"]

 */

import Foundation

class Solution {
    func reverseString(_ s: inout [Character]) {
        // 为了实现 reverse() 函数
        var i = 0
        var j = s.count - 1
        while i < j {
            s.swapAt(i, j)
            i += 1
            j -= 1
        }
    }
}