LeetCode-in-Java

2870. Minimum Number of Operations to Make Array Empty

Medium

You are given a 0-indexed array nums consisting of positive integers.

There are two types of operations that you can apply on the array any number of times:

• Choose two elements with equal values and delete them from the array.
• Choose three elements with equal values and delete them from the array.

Return the minimum number of operations required to make the array empty, or -1 if it is not possible.

Example 1:

Input: nums = [2,3,3,2,2,4,2,3,4]

Output: 4

Explanation: We can apply the following operations to make the array empty:

• Apply the first operation on the elements at indices 0 and 3. The resulting array is nums = [3,3,2,4,2,3,4].
• Apply the first operation on the elements at indices 2 and 4. The resulting array is nums = [3,3,4,3,4].
• Apply the second operation on the elements at indices 0, 1, and 3. The resulting array is nums = [4,4].
• Apply the first operation on the elements at indices 0 and 1. The resulting array is nums = [].

It can be shown that we cannot make the array empty in less than 4 operations.

Example 2:

Input: nums = [2,1,2,2,3,3]

Output: -1

Explanation: It is impossible to empty the array.

Constraints:

• 2 <= nums.length <= 105
• 1 <= nums[i] <= 106

Solution

import java.util.Arrays;

public class Solution {
    public int minOperations(int[] nums) {
        Arrays.sort(nums);
        int count;
        int min = 0;
        int current;
        int i = 0;
        while (i < nums.length) {
            current = nums[i];
            count = 0;
            while (i < nums.length && current == nums[i]) {
                count += 1;
                i++;
            }
            if (count == 1) {
                return -1;
            }
            min += (int) Math.ceil(count / (3 * 1.0));
        }
        return min;
    }
}

This site is open source. Improve this page.