LeetCode-in-Java

2576. Find the Maximum Number of Marked Indices

Medium

You are given a 0-indexed integer array nums.

Initially, all of the indices are unmarked. You are allowed to make this operation any number of times:

• Pick two different unmarked indices i and j such that 2 * nums[i] <= nums[j], then mark i and j.

Return the maximum possible number of marked indices in nums using the above operation any number of times.

Example 1:

Input: nums = [3,5,2,4]

Output: 2

Explanation: In the first operation: pick i = 2 and j = 1, the operation is allowed because 2 * nums[2] <= nums[1]. Then mark index 2 and 1. It can be shown that there’s no other valid operation so the answer is 2.

Example 2:

Input: nums = [9,2,5,4]

Output: 4

Explanation: In the first operation: pick i = 3 and j = 0, the operation is allowed because 2 * nums[3] <= nums[0].

Then mark index 3 and 0.

In the second operation: pick i = 1 and j = 2, the operation is allowed because 2 * nums[1] <= nums[2]. Then mark index 1 and 2.

Since there is no other operation, the answer is 4.

Example 3:

Input: nums = [7,6,8]

Output: 0

Explanation: There is no valid operation to do, so the answer is 0.

Constraints:

• 1 <= nums.length <= 105
• 1 <= nums[i] <= 109

Solution

import java.util.Arrays;

public class Solution {
    public int maxNumOfMarkedIndices(int[] nums) {
        Arrays.sort(nums);
        int i = 0;
        int j = nums.length / 2;
        long count = 0;
        while (i < nums.length / 2 && j < nums.length) {
            if (nums[i] * 2 <= nums[j]) {
                i++;
                j++;
                count = count + 2;
            } else {
                j++;
            }
        }
        return (int) count;
    }
}

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