344. Reverse String

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"]

Solution

    public void reverseString(char[] s) {
        for(int i = 0; i < s.length; i++){
            int j = s.length - i - 1;
            if(i >= j){
                break;
            }else
                swap(s, i, j);
        }
    }
    
    public void swap(char[] s, int i, int j){
        if(i != j){
            char temp = s[i];
            s[i] = s[j];
            s[j] = temp;
        }
    }