LeetCode Solution - Problem Reverse String

• Write a function that reverses a string. The input string is given as an array of characters s.
• You must do this by modifying the input array in-place with O(1) extra memory.

Example 1:

Input: s = ["h","e","l","l","o"]
Output: ["o","l","l","e","h"]

Example 2:

Input: s = ["H","a","n","n","a","h"]
Output: ["h","a","n","n","a","H"]

Constraints:

• 1 <= s.length <= 105
• s[i] is a printable ASCII character.

Solution:

Java:

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

        while (left < right) {
            char tmp = s[left];
            s[left] = s[right];
            s[right] = tmp;
            left++;
            right--;
        }
    }
}

/* TC: O(n), SC: O(1) */

Python:

class Solution:
    def reverseString(self, s: List[str]) -> None:
        """
        Do not return anything, modify s in-place instead.
        """
        s[:] = s[::-1]
        return s