Find earliest common meeting slot

Problem Statement

You are tasked with scheduling a meeting of duration d (in minutes) for a group of employees. Each employee has a list of busy intervals [start, end) (in minutes from the start of the day) and a working shift defined by [shift_start, shift_end).

Find the earliest time t such that for all employees, the interval [t, t + d) is entirely within their working shift and does not overlap with any of their busy intervals. If no such time exists within a given day range [0, 1440), return -1.

Function Signature

find_earliest_slot(schedules, working_hours, d)

• schedules: A list of lists, where schedules[i] contains sorted disjoint busy intervals for employee i.
• working_hours: A list of pairs [start, end] for each employee.
• d: An integer representing the required meeting duration.

Example

# schedules = [[[100, 200]], [[150, 250]]]
# working_hours = [[0, 500], [0, 500]]
# d = 60
# Output: 0 
# Explanation: The range [0, 60] is free for both. 

Constraints

• 0 <= d <= 1440
• schedules are always sorted and non-overlapping.
• Number of employees N is up to 1000.
• Total number of busy intervals across all employees is M.