344. Reverse String.cpp

/*
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"]

First solution using swap from start -> mid
Solution two using XOR
*/
class Solution {
public:
    void reverseString(vector<char>& s) {
        int i = 0, j = s.size() - 1;
        while ( i < j )
        {
            swap( s[i++], s[j--] );
        }

    }
};

class Solution {
public:
    void reverseString(vector<char>& s) {
        int i = 0, j = s.size() - 1;
        while ( i < j )
        {
            s[i] = s[i] ^ s[j];
            s[j] = s[i] ^ s[j];
            s[i] = s[i] ^ s[j];
            ++i; --j;
        }

    }
};