#2336 - Smallest Number in Infinite Set

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Problem Description

You have a set which contains all positive integers [1, 2, 3, 4, 5, ...].

Implement the SmallestInfiniteSet class:

SmallestInfiniteSet() Initializes the SmallestInfiniteSet object to contain all positive integers.
int popSmallest() Removes and returns the smallest integer contained in the infinite set.
void addBack(int num) Adds a positive integer num back into the infinite set, if it is not already in the infinite set.

Solution

var SmallestInfiniteSet = function() {
  this.set = new Array(1000).fill(1);
};

/**
 * @return {number}
 */
SmallestInfiniteSet.prototype.popSmallest = function() {
  const num = this.set.findIndex(n => n);
  this.set[num] = 0;
  return num + 1;
};

/**
 * @param {number} num
 * @return {void}
 */
SmallestInfiniteSet.prototype.addBack = function(num) {
  this.set[num - 1] = 1;
};