leetcode-268 丢失的数字

/**
 * @param {number[]} nums
 * @return {number}
 */
var missingNumber = function (nums) {
  const bank = nums.slice();
  bank.sort((a, b) => a - b);
  for (let i = 0; i <= bank.length; i++) {
    if (bank[i] !== i) return i;
  }
};

/**
 * @param {number[]} nums
 * @return {number}
 */
var missingNumber = function (nums) {
  const n = nums.length;
  let sum = ((1 + n) * n) / 2;
  for (let i = 0; i < n; i++) {
    sum -= nums[i];
  }
  return sum;
};
// console.log(missingNumber([3, 0, 1]));

function missingNumber(nums) {
  let res = nums.length;
  for (let i = 0; i < nums.length; i++) {
    res ^= i ^ nums[i];
  }
  return res;
}