LeetCode Reverse String

原题链接在这里：https://leetcode.com/problems/reverse-string/

题目：

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"]

题解：

Reverse string是常见题, string在Java中是primitive类型, 一旦生成不可改变.

But we have the array of char here. Then use two pointers. Remember to move pointer in while loop.

Time Complexity: O(s.length).

Space: O(1).

AC Java:

 class Solution {
     public void reverseString(char[] s) {
         int l = 0;
         int r = s.length - 1;

         while(l < r){
             char temp = s[l];
             s[l] = s[r];
             s[r] = temp;

             l++;
             r--;
         }
     }
 }

跟上Reverse String II, Reverse Vowels of a String.