2099. Find Subsequence of Length K With the Largest Sum

Problem Link

Description

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You are given an integer array nums and an integer k. You want to find a subsequence of nums of length k that has the largest sum.

Return any such subsequence as an integer array of length k.

A subsequence is an array that can be derived from another array by deleting some or no elements without changing the order of the remaining elements.

 

Example 1:

Input: nums = [2,1,3,3], k = 2
Output: [3,3]
Explanation:
The subsequence has the largest sum of 3 + 3 = 6.

Example 2:

Input: nums = [-1,-2,3,4], k = 3
Output: [-1,3,4]
Explanation: 
The subsequence has the largest sum of -1 + 3 + 4 = 6.

Example 3:

Input: nums = [3,4,3,3], k = 2
Output: [3,4]
Explanation:
The subsequence has the largest sum of 3 + 4 = 7. 
Another possible subsequence is [4, 3].

 

Constraints:

• 1 <= nums.length <= 1000
• -105 <= nums[i] <= 105
• 1 <= k <= nums.length

Solution

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Python3

class Solution:
    def maxSubsequence(self, nums: List[int], k: int) -> List[int]:
        pq = []
        for i, x in enumerate(nums):
            if len(pq) == k:
                heappushpop(pq, (x, i))
            else:
                heappush(pq, (x, i))
                
        idx = [i for _, i in pq]
        idx.sort()
        
        return [nums[i] for i in idx]