LeetCode-in-Java

2848. Points That Intersect With Cars

Easy

You are given a 0-indexed 2D integer array nums representing the coordinates of the cars parking on a number line. For any index i, nums[i] = [starti, endi] where starti is the starting point of the ith car and endi is the ending point of the ith car.

Return the number of integer points on the line that are covered with any part of a car.

Example 1:

Input: nums = [[3,6],[1,5],[4,7]]

Output: 7

Explanation: All the points from 1 to 7 intersect at least one car, therefore the answer would be 7.

Example 2:

Input: nums = [[1,3],[5,8]]

Output: 7

Explanation: Points intersecting at least one car are 1, 2, 3, 5, 6, 7, 8. There are a total of 7 points, therefore the answer would be 7.

Constraints:

• 1 <= nums.length <= 100
• nums[i].length == 2
• 1 <= starti <= endi <= 100

Solution

import java.util.List;

public class Solution {
    public int numberOfPoints(List<List<Integer>> nums) {
        int min = 101;
        int max = 0;
        int[] count = new int[102];
        for (List<Integer> list : nums) {
            int num1 = list.get(0);
            int num2 = list.get(1);

            if (num1 < min) {
                min = num1;
            }
            if (num2 > max) {
                max = num2;
            }

            count[num1]--;
            count[num2 + 1]++;
        }

        int result = 0;
        int balance = 0;
        for (; min <= max; min++) {
            balance += count[min];
            if (balance < 0) {
                result++;
            }
        }
        return result;
    }
}

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