What is the time complexity of LeetCode 2557. Maximum Number of Integers to Choose From a Range II?

The Python solution on this page runs in O(n \times \log n).

What is the space complexity of LeetCode 2557. Maximum Number of Integers to Choose From a Range II?

The Python solution on this page uses O(n) auxiliary space.

Maximum Number of Integers to Choose From a Range II — LeetCode 2557 Python Solution

MediumLeetCode PremiumGreedyArrayBinary SearchSorting

Problem: #2557
Pattern: Monotonic Stack
Reading time: 3 min
Source: leetcode.com

The problem

You are given an integer array banned and two integers n and maxSum. You are choosing some number of integers following the below rules: The chosen integers have to be in the range [1, n].

Example

Input: banned = [1,4,6], n = 6, maxSum = 4
Output: 1
Explanation: You can choose the integer 3.

Python solution

Python

class Solution:
    def maxCount(self, banned: List[int], n: int, maxSum: int) -> int:
        banned.extend([0, n + 1])
        ban = sorted(set(banned))
        ans = 0
        for i, j in pairwise(ban):
            left, right = 0, j - i - 1
            while left < right:
                mid = (left + right + 1) >> 1
                if (i + 1 + i + mid) * mid // 2 <= maxSum:
                    left = mid
                else:
                    right = mid - 1
            ans += left
            maxSum -= (i + 1 + i + left) * left // 2
            if maxSum <= 0:
                break
        return ans

Complexity

Measure	Complexity
Time	O(n \times \log n)
Space	O(n) auxiliary

Pattern: Monotonic Stack

Answer "what is the next greater element" for every position in one pass. LeetCode 2557. Maximum Number of Integers to Choose From a Range II is filed here because the reference solution below belongs to the algorithm family this hub collects, even though its LeetCode tags point elsewhere.

The monotonic stack guide has the Python template for the pattern and the 225 LeetCode problems that use it.

Frequently asked questions

How hard is LeetCode 2557. Maximum Number of Integers to Choose From a Range II?: LeetCode 2557. Maximum Number of Integers to Choose From a Range II is rated Medium on LeetCode.
What is the time complexity of LeetCode 2557. Maximum Number of Integers to Choose From a Range II?: The Python solution on this page runs in O(n \times \log n).
What is the space complexity of LeetCode 2557. Maximum Number of Integers to Choose From a Range II?: The Python solution on this page uses O(n) auxiliary space.
What topics does LeetCode 2557. Maximum Number of Integers to Choose From a Range II cover?: LeetCode 2557. Maximum Number of Integers to Choose From a Range II is tagged Greedy, Array, Binary Search and Sorting on LeetCode.
Is LeetCode 2557. Maximum Number of Integers to Choose From a Range II a premium problem?: Yes. LeetCode 2557. Maximum Number of Integers to Choose From a Range II is a LeetCode Premium problem, so the full statement and test cases require a paid LeetCode subscription.