2357. Make Array Zero by Subtracting Equal Amounts

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.

class Solution {
public:
    int minimumOperations(vector<int>& nums) {
        unordered_set<int> us(begin(nums), end(nums));
        return us.size() - us.count(0);
    }
};