'''
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.



'''


class Solution:
    def reverseString(self, s: List[str]) -> None:
        """
        Do not return anything, modify s in-place instead.
        """
        left = 0
        right = len(s) - 1

        while left != right:
            s[left], s[right] = s[right], s[left]
            left += 1
            if left == right:
                break
            right -= 1