82. find available meeting slots

[start, end] is a time interval, with all integers from 0 to 24.

Given schedules for all team members,

[
  [[13,15], [11,12], [10,13]], //schedule for member 1
  [[8, 9]], // schedule for member 2
  [[13, 18]] // schedule for member 3
]

You need to create a function findMeetingSlots() to return the time slots available for all the members to have a meeting.

For the input above, below slots should be returned

[[0,8],[9,10],[18,24]]

Notes

1. the input schedule intervals might be unsorted
2. one member's schedule might have overlapping intervals.