2336-smallest-number-in-infinite-set.rb

# frozen_string_literal: true

# 2336. Smallest Number in Infinite Set
# https://leetcode.com/problems/smallest-number-in-infinite-set
# Medium

=begin
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.

Example 1:
Input
["SmallestInfiniteSet", "addBack", "popSmallest", "popSmallest", "popSmallest", "addBack", "popSmallest", "popSmallest", "popSmallest"]
[[], [2], [], [], [], [1], [], [], []]
Output
[null, null, 1, 2, 3, null, 1, 4, 5]

Explanation
SmallestInfiniteSet smallestInfiniteSet = new SmallestInfiniteSet();
smallestInfiniteSet.addBack(2);    // 2 is already in the set, so no change is made.
smallestInfiniteSet.popSmallest(); // return 1, since 1 is the smallest number, and remove it from the set.
smallestInfiniteSet.popSmallest(); // return 2, and remove it from the set.
smallestInfiniteSet.popSmallest(); // return 3, and remove it from the set.
smallestInfiniteSet.addBack(1);    // 1 is added back to the set.
smallestInfiniteSet.popSmallest(); // return 1, since 1 was added back to the set and
                                   // is the smallest number, and remove it from the set.
smallestInfiniteSet.popSmallest(); // return 4, and remove it from the set.
smallestInfiniteSet.popSmallest(); // return 5, and remove it from the set.


Constraints:
1 <= num <= 1000
At most 1000 calls will be made in total to popSmallest and addBack.
=end

class SmallestInfiniteSet
  def initialize
    @t = CRBTreeMap.new
    @c = 0
  end


=begin
    :rtype: Integer
=end
  def pop_smallest
    @t.empty? ? @c += 1 : @t.delete_min
  end


=begin
    :type num: Integer
    :rtype: Void
=end
  def add_back(num)
    @t[num] = num if num <= @c
  end
end

# Your SmallestInfiniteSet object will be instantiated and called as such:
# obj = SmallestInfiniteSet.new()
# param_1 = obj.pop_smallest()
# obj.add_back(num)