link to leedcode problem definition

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"]

This can be solved with an approach called two pointers:

1. Iterate through the array of charecters till half
2. Swap chars from start and end

class Solution {
    public void reverseString(char[] s) {
        var size = s.length;
        for(int i = 0; i < size / 2; i++) {
            char c = s[i];
            s[i] = s[size - i - 1];
            s[size - i - 1] = c;
        } 
    }
}