Determine the Minimum Sum of a k-avoiding Array — LeetCode 2829 Python Solution

The problem

You are given two integers, n and k. An array of distinct positive integers is called a k-avoiding array if there does not exist any pair of distinct elements that sum to k.

Example

Input

n = 5, k = 4

Output

18

Explanation

Consider the k-avoiding array [1,2,4,5,6], which has a sum of 18.

Python solution

class Solution:
    def minimumSum(self, n: int, k: int) -> int:
        s, i = 0, 1
        vis = set()
        for _ in range(n):
            while i in vis:
                i += 1
            vis.add(k - i)
            s += i
            i += 1
        return s

Complexity

Pattern: Greedy

Take the locally best option every time — when you can prove that never costs you later. LeetCode 2829. Determine the Minimum Sum of a k-avoiding Array is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Greedy.

The greedy guide has the Python template for the pattern and the 346 LeetCode problems that use it.

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