LeetCode-in-Java

2453. Destroy Sequential Targets

Medium

You are given a 0-indexed array nums consisting of positive integers, representing targets on a number line. You are also given an integer space.

You have a machine which can destroy targets. Seeding the machine with some nums[i] allows it to destroy all targets with values that can be represented as nums[i] + c * space, where c is any non-negative integer. You want to destroy the maximum number of targets in nums.

Return the minimum value of nums[i] you can seed the machine with to destroy the maximum number of targets.

Example 1:

Input: nums = [3,7,8,1,1,5], space = 2

Output: 1

Explanation: If we seed the machine with nums[3], then we destroy all targets equal to 1,3,5,7,9,… In this case, we would destroy 5 total targets (all except for nums[2]). It is impossible to destroy more than 5 targets, so we return nums[3].

Example 2:

Input: nums = [1,3,5,2,4,6], space = 2

Output: 1

Explanation: Seeding the machine with nums[0], or nums[3] destroys 3 targets. It is not possible to destroy more than 3 targets. Since nums[0] is the minimal integer that can destroy 3 targets, we return 1.

Example 3:

Input: nums = [6,2,5], space = 100

Output: 2

Explanation: Whatever initial seed we select, we can only destroy 1 target. The minimal seed is nums[1].

Constraints:

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

Solution

import java.util.HashMap;

public class Solution {
    public int destroyTargets(int[] nums, int space) {
        HashMap<Integer, Integer> map = new HashMap<>();
        for (int num : nums) {
            int reminder = num % space;
            int freq = map.getOrDefault(reminder, 0);
            map.put(reminder, freq + 1);
        }
        int maxCount = 0;
        int ans = Integer.MAX_VALUE;
        for (int count : map.values()) {
            maxCount = Math.max(count, maxCount);
        }
        for (int val : nums) {
            if (map.get(val % space) == maxCount) {
                ans = Math.min(ans, val);
            }
        }
        return ans;
    }
}

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