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LeetCode solutions

2413. Smallest Number in Infinite Set

My accepted Python solution to LeetCode problem 2413, Smallest Number in Infinite Set, running in 16ms.

  • Difficulty: Medium
  • Python
  • Runtime 16ms
  • Memory 17.9MB

Read the problem on LeetCode View on GitHub

The problem statement is LeetCode’s and stays on their site. What follows is my accepted solution.

Python

Accepted on LeetCode — runtime 16ms, memory 17.9MB, accepted 2025-12-29.

python
class SmallestInfiniteSet:
    def __init__(self):
        self.cur = 1
        self.s = set()

    def popSmallest(self) -> int:
        if self.s:
            res = min(self.s)
            self.s.remove(res)
            return res
        self.cur += 1
        return self.cur - 1

    def addBack(self, num: int) -> None:
        if num < self.cur:
            self.s.add(num)

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