#846 · #3169 · Count Days Without Meetings(无需开会的工作日)

You are given a positive integer days representing a 1-indexed schedule of days days, and an array meetings where meetings[i] = [start_i, end_i] is a busy interval. Return the number of days with no meetings. Constraints: 1 <= days <= 10^9, 1 <= meetings.length <= 10^5, 1 <= start_i <= end_i <= days.