344__easy__reverse-string.js

/**

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"]

 */
/**
 *
 * O(n) time
 * O(1) space
 *
 * 5m
 */
var reverseString = function (s) {
  let lo = 0;
  let hi = s.length - 1;
  while (lo < hi) {
    [s[lo], s[hi]] = [s[hi], s[lo]];
    lo++;
    hi--;
  }
};