solutions/0810-chalkboard-xor-game.js

/**
 * 810. Chalkboard XOR Game
 * https://leetcode.com/problems/chalkboard-xor-game/
 * Difficulty: Hard
 *
 * You are given an array of integers nums represents the numbers written on a chalkboard.
 *
 * Alice and Bob take turns erasing exactly one number from the chalkboard, with Alice starting
 * first. If erasing a number causes the bitwise XOR of all the elements of the chalkboard to
 * become 0, then that player loses. The bitwise XOR of one element is that element itself, and
 * the bitwise XOR of no elements is 0.
 *
 * Also, if any player starts their turn with the bitwise XOR of all the elements of the chalkboard
 * equal to 0, then that player wins.
 *
 * Return true if and only if Alice wins the game, assuming both players play optimally.
 */

/**
 * @param {number[]} nums
 * @return {boolean}
 */
var xorGame = function(nums) {
  const total = nums.reduce((xor, num) => xor ^ num, 0);
  if (total === 0) return true;
  return nums.length % 2 === 0;
};