1681. Minimum Incompatibility

https://leetcode.com/problems/minimum-incompatibility

Description

You are given an integer array nums​​​ and an integer k. You are asked to distribute this array into k subsets of equal size such that there are no two equal elements in the same subset.

A subset's incompatibility is the difference between the maximum and minimum elements in that array.

Return the minimum possible sum of incompatibilities of the k subsets after distributing the array optimally, or return -1 if it is not possible.

A subset is a group integers that appear in the array with no particular order.

Example 1:

**Input:** nums = [1,2,1,4], k = 2
**Output:** 4
**Explanation:** The optimal distribution of subsets is [1,2] and [1,4].
The incompatibility is (2-1) + (4-1) = 4.
Note that [1,1] and [2,4] would result in a smaller sum, but the first subset contains 2 equal elements.

Example 2:

**Input:** nums = [6,3,8,1,3,1,2,2], k = 4
**Output:** 6
**Explanation:** The optimal distribution of subsets is [1,2], [2,3], [6,8], and [1,3].
The incompatibility is (2-1) + (3-2) + (8-6) + (3-1) = 6.

Example 3:

**Input:** nums = [5,3,3,6,3,3], k = 3
**Output:** -1
**Explanation:** It is impossible to distribute nums into 3 subsets where no two elements are equal in the same subset.

Constraints:

• 1 <= k <= nums.length <= 16

• nums.length is divisible by k

• 1 <= nums[i] <= nums.length

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