LC 448. Find All Numbers Disappeared in an Array

/**
 * @param {number[]} nums
 * @return {number[]}
 */
var findDisappearedNumbers = function(nums) {
  const n = nums.length
  for (const num of nums) {
    const x = (num - 1) % n
    nums[x] += n
  }
  const ret = []
  for (const [i, num] of nums.entries()) {
    if (num <= n) {
      ret.push(i + 1)
    }
  }
  return ret
};