344. Reverse String

Easy

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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.

class Solution:
    def reverseString(self, s: List[str]) -> None:
        left, right = 0, len(s)-1
        while left <= right:
            s[left], s[right] = s[right], s[left]
            left += 1
            right -= 1