Ezvor

3139. Minimum Cost to Equalize Array

HardArray Preparing judge… LeetCode

You are given an integer array nums and two integers cost1 and cost2. You are allowed to perform either of the following operations any number of times:

  • Choose an index i from nums and increase nums[i] by 1 for a cost of cost1.
  • Choose two different indices i, j, from nums and increase nums[i] and nums[j] by 1 for a cost of cost2.

Return the minimum cost required to make all elements in the array equal.

Since the answer may be very large, return it modulo 109 + 7.

 

Example 1:

Input: nums = [4,1], cost1 = 5, cost2 = 2

Output: 15

Explanation:

The following operations can be performed to make the values equal:

  • Increase nums[1] by 1 for a cost of 5. nums becomes [4,2].
  • Increase nums[1] by 1 for a cost of 5. nums becomes [4,3].
  • Increase nums[1] by 1 for a cost of 5. nums becomes [4,4].

The total cost is 15.

Example 2:

Input: nums = [2,3,3,3,5], cost1 = 2, cost2 = 1

Output: 6

Explanation:

The following operations can be performed to make the values equal:

  • Increase nums[0] and nums[1] by 1 for a cost of 1. nums becomes [3,4,3,3,5].
  • Increase nums[0] and nums[2] by 1 for a cost of 1. nums becomes [4,4,4,3,5].
  • Increase nums[0] and nums[3] by 1 for a cost of 1. nums becomes [5,4,4,4,5].
  • Increase nums[1] and nums[2] by 1 for a cost of 1. nums becomes [5,5,5,4,5].
  • Increase nums[3] by 1 for a cost of 2. nums becomes [5,5,5,5,5].

The total cost is 6.

Example 3:

Input: nums = [3,5,3], cost1 = 1, cost2 = 3

Output: 4

Explanation:

The following operations can be performed to make the values equal:

  • Increase nums[0] by 1 for a cost of 1. nums becomes [4,5,3].
  • Increase nums[0] by 1 for a cost of 1. nums becomes [5,5,3].
  • Increase nums[2] by 1 for a cost of 1. nums becomes [5,5,4].
  • Increase nums[2] by 1 for a cost of 1. nums becomes [5,5,5].

The total cost is 4.

 

Constraints:

  • 1 <= nums.length <= 105
  • 1 <= nums[i] <= 106
  • 1 <= cost1 <= 106
  • 1 <= cost2 <= 106
ArrayGreedyEnumeration

Hints

Hint 1
How can you determine the minimum cost if you know the maximum value in the array once all values are made equal?
Hint 2
If cost2 > cost1 * 2, we should just use cost1 to change all the values to the maximum one.
Hint 3
Otherwise, it's optimal to choose the smallest two values and use cost2 to increase both of them.
Hint 4
Since the maximum value is known, calculate the required increases to equalize all values, instead of naively simulating the operations.
Hint 5
There are not a lot of candidates for the maximum; we can try all of them and choose which uses the minimum number of operations.