344. Reverse String

description： Write a function that reverses a string. The input string is given as an array of characters char[].

require： 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’]

First Edition

class Solution {
    public void reverseString(char[] s) {
        for(int i = 0; i < s.length >>> 1; i++) {
            s[i] = (char)(s[i] ^ s[s.length - i - 1]);
            s[s.length - i -1] = (char)(s[i] ^ s[s.length -i - 1]);
            s[i] = (char)(s[i] ^ s[s.length - i - 1]);
        }
    }
}

Runtime: 18 ms, faster than 12.93% of Java online submissions for Reverse String.

SECOND EDITION

class Solution {
    public void reverseString(char[] s) {
        int length = s.length;
        for(int i = 0; i < length >>> 1; i++) {
            s[i] = (char)(s[i] ^ s[length - i - 1]);
            s[length - i -1] = (char)(s[i] ^ s[length -i - 1]);
            s[i] = (char)(s[i] ^ s[length - i - 1]);
        }
    }
}

Runtime: 12 ms, faster than 95.19% of Java online submissions for Reverse String.