Description Link to heading

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

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

Solution Link to heading

Greedy algorithm: for each operation, we subtract the smallest non-zero element in nums, so the result is the amount of types of non-zero elements in nums.

Code Link to heading 

class Solution {
  public:
    int minimumOperations(vector<int> &nums) {
        unordered_map<int, int> mp;
        for (int &num : nums) {
            if (num != 0) {
                mp[num]++;
            }
        }
        return mp.size();
    }
};