Solution: Find the K-Sum of an Array
Let’s solve the Find the K-Sum of an Array problem using the Top K Element Pattern.
We'll cover the following
Statement
You are given an integer array, nums
, and a positive integer k
. Your task is to determine and return the
Remember: For valid subsequences:
The empty subsequence is valid, and its sum is considered
. Duplicate subsequence sums are allowed and counted separately when determining the
largest.
Constraints:
nums.length
n
nums[i]
k
Solution
A brute-force approach to this problem will involve generating all possible subsequences of the array. Since an array of length n has exactly n
(up to 1000).
To solve the problem efficiently, we reframe the task: instead of directly computing the
Thus, finding the
To compute these losses, we transform the problem as follows:
Convert all elements to absolute values—as excluding positives or including negatives both reduce the total.
Sort this array to prioritize smaller losses.
Use a min heap to systematically explore the smallest reduction combinations.
We initialize the heap with (loss =
Including the current value: (currLoss + nums[i], i+1)
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