Count Days Without Meetings

You are given a positive integer days representing the total number of days an employee is available for work (starting from day 1). You are also given a 2D array meetings of size n where, meetings[i] = [start_i, end_i] represents the starting and ending days of meeting i (inclusive).

Return the count of days when the employee is available for work but no meetings are scheduled.

Note: The meetings may overlap.

LeetCode Problem - 3169

class Solution {
    public int countDays(int days, int[][] meetings) {
        // Sort the meetings array based on the start time of each meeting
        Arrays.sort(meetings, Comparator.comparingInt(a -> a[0]));

        // Initialize the start to one day before the first meeting's start time
        // and end to the end time of the first meeting
        int start = meetings[0][0] - 1, end = meetings[0][1];

        // Iterate through the sorted meetings starting from the second meeting
        for (int i = 1; i < meetings.length; i++) {
            // If there is a gap between the end of the current meeting and the start of the next meeting,
            // add the number of days in the gap to the start
            if (end < meetings[i][0]) start += meetings[i][0] - end - 1;

            // Update the end to be the maximum of the current end and the end of the current meeting
            end = Math.max(end, meetings[i][1]);
        }

        // Calculate the number of days between the total days and the end time of the last meeting
        // and add this to the start to get the total count of days
        return start + days - end;
    }
}