Find Common Available Time Slots in Google Calendar

Problem: Find Common Available Time Slots in Google Calendar Given the busy schedules of n people in Google Calendar, where each busy interval is represented as a half-open interval [start, end) in minutes, a valid working window [workStart, workEnd), and a required meeting length duration. Return all time intervals [start, end) where a meeting can be scheduled such that: the interval is fully inside [workStart, workEnd); no participant has a conflicting busy event; the interval length is at least duration; intervals are returned in ascending order by start time; if no such interval exists, print None. Input Format n duration workStart workEnd m1 start end ... m2 start end ... Where: n is the number of participants; the i-th participant has mi busy intervals; all times are integer minutes; busy intervals may be unsorted, overlapping, or adjacent. Output Format Print each available interval on a separate line: start end If no interval exists, print: None Constraints 1 <= n <= 10^5 Total number of busy intervals M <= 2 * 10^5 0 <= workStart < workEnd <= 10^9 1 <= duration <= workEnd - workStart 0 <= start < end <= 10^9 Example Input: 2 30 540 1020 2 540 600 720 780 2 570 630 900 960 Output: 630 720 780 900 960 1020 Example Input 2 30 540 1020 2 540 600 720 780 2 570 630 900 960 Output 630 720 780 900 960 1020