Package g2301_2400.s2336_smallest_number_in_infinite_set

Class SmallestInfiniteSet

java.lang.Object
g2301_2400.s2336_smallest_number_in_infinite_set.SmallestInfiniteSet
public class SmallestInfiniteSet extends java.lang.Object
2336 - Smallest Number in Infinite Set.

Medium

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.

  • Constructor Summary

    Constructors
    Constructor
    Description
    SmallestInfiniteSet()
     

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    addBack(int num)
     
    int
    popSmallest()
     

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Constructor Details

    • SmallestInfiniteSet

      public SmallestInfiniteSet()

  • Method Details

    • popSmallest

      public int popSmallest()

    • addBack

      public void addBack(int num)