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2099. Find Subsequence of Length K with the Largest Sum

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Problem Statement

2099. Find Subsequence of Length K With the Largest Sum

Easy


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:

Java — 2 heaps

Source file
class Solution {
    public int[] maxSubsequence(int[] nums, int k) {
        Queue<int[]> pq1 = new PriorityQueue<>((a, b) -> b[0] - a[0]);
        Queue<int[]> pq2 = new PriorityQueue<>((a, b) -> a[1] - b[1]);
        for (int i = 0; i < nums.length; i++)
            pq1.offer(new int[] { nums[i], i });
        for (int i = 0; i < k; i++)
            pq2.offer(pq1.poll());
        int[] ans = new int[k];
        int i = 0;
        while (!pq2.isEmpty())
            ans[i++] = pq2.poll()[0];
        return ans;
    }
}