Find the Most Competitive Subsequence

Find the Most Competitive Subsequence is a Medium Data Structures and Algorithms interview problem you can solve, run and submit on Thita.ai. It belongs to the Stack Patterns pattern, in the Monotonic Stack subpattern.

Problem statement

Given an integer array nums and a positive integer k, return the most competitive subsequence of nums of size k.

An array's subsequence is a resulting sequence obtained by erasing some (possibly zero) elements from the array.

We define that a subsequence a is more competitive than a subsequence b (of the same length) if in the first position where a and b differ, subsequence a has a number less than the corresponding number in b. For example, [1,3,4] is more competitive than [1,3,5] because the first position they differ is at the final number, and 4 is less than 5.

Example 1:

Input: nums = [3,5,2,6], k = 2 Output: [2,6] Explanation: Among the set of every possible subsequence: {[3,5], [3,2], [3,6], [5,2], [5,6], [2,6]}, [2,6] is the most competitive.

Example 2:

Input: nums = [2,4,3,3,5,4,9,6], k = 4 Output: [2,3,3,4]

Constraints:

- 1 <= nums.length <= 105

- 0 <= nums[i] <= 109

- 1 <= k <= nums.length

Topics and companies

Topics: Array, Stack, Greedy, Monotonic Stack.

Reported in interviews at Amazon.

How to practise Find the Most Competitive Subsequence on Thita.ai

Starter code is provided in C, C#, C++, Go, Java, JavaScript and Python. Your solution runs against 5 test cases for this problem, with the AI coach available for a hint when you are stuck rather than a finished answer. The reference solution runs in O(n) time and O(k) space.

Open Find the Most Competitive Subsequence in the code editor, or read the Find the Most Competitive Subsequence editorial for a worked solution with its approach and complexity analysis.

Where Find the Most Competitive Subsequence sits in the DSA pattern sheet

Problems related to Find the Most Competitive Subsequence

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