Find the Most Competitive Subsequence — LeetCode 1673 Python Solution

The problem

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.

Example

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.

Python solution

class Solution:
    def mostCompetitive(self, nums: List[int], k: int) -> List[int]:
        stk = []
        n = len(nums)
        for i, v in enumerate(nums):
            while stk and stk[-1] > v and len(stk) + n - i > k:
                stk.pop()
            if len(stk) < k:
                stk.append(v)
        return stk

Complexity

Pattern: Stack

When the most recent unresolved thing is the one that matters, use a stack. LeetCode 1673. Find the Most Competitive Subsequence is filed here because LeetCode tags it Stack, which is the vocabulary this hub collects.

The stack guide has the Python template for the pattern and the 194 LeetCode problems that use it.

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