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2357 - Make Array Zero by Subtracting Equal Amounts (Easy)

https://leetcode.com/problems/make-array-zero-by-subtracting-equal-amounts

Problem Statement​

You are given a non-negative integer array nums. In one operation, you must:

  • Choose a positive integer x such that x is less than or equal to the smallest non-zero element in nums.
  • Subtract x from every positive element in nums.

Return the minimum number of operations to make every element in nums equal to 0.

Example 1:

Input: nums = [1,5,0,3,5]
Output: 3
Explanation:
In the first operation, choose x = 1. Now, nums = [0,4,0,2,4].
In the second operation, choose x = 2. Now, nums = [0,2,0,0,2].
In the third operation, choose x = 2. Now, nums = [0,0,0,0,0].

Example 2:

Input: nums = [0]
Output: 0
Explanation: Each element in nums is already 0 so no operations are needed.

Constraints:

  • 1 <= nums.length <= 100
  • 0 <= nums[i] <= 100

Approach: Counting​

Observations:

  • We can remove all numbers x in one go
  • We need nn moves to remove nn distinct numbers
  • Hence, the problem is to find out the number of different positive numbers
Written by @wingkwong
func minimumOperations(nums []int) int {
    s := make(map[int]bool)
    for _, v := range nums {
        if v > 0 { 
            s[v] = true
        }
    }
    return len(s)
}