Leetcode•Nov 01, 2026

Reverse String

Hazrat Ali

Leetcode

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"]

Solution
var reverseString = function(s) {
    let left = 0;
    let right = s.length - 1;

    while (left < right) {
        [s[left], s[right]] = [s[right], s[left]];

        left++;
        right--;
    }
};
 

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