289. My Calendar II

You are implementing a program to use as your calendar. We can add a new event if adding the event will not cause a **triple booking**. A **triple booking** happens when three events have some non-empty intersection (i.e., some moment is common to all the three events.) The event can be represented as a pair of integers `start` and `end` that represents a booking on the half-open interval `[start, end)`, the range of real numbers `x` such that `start <= x < end`. Implement the `MyCalendarTwo` class: - `MyCalendarTwo()` Initializes the calendar object. - `boolean book(int start, int end)` Returns `true` if the event can be added to the calendar successfully without causing a **triple booking**. Otherwise, return `false` and do not add the event to the calendar.