<p>You are implementing a program to use as your calendar. We can add a new event if adding the event will not cause a <strong>triple booking</strong>.</p>
<p>A <strong>triple booking</strong> happens when three events have some non-empty intersection (i.e., some moment is common to all the three events.).</p>
<p>The event can be represented as a pair of integers <code>start</code> and <code>end</code> that represents a booking on the half-open interval <code>[start, end)</code>, the range of real numbers <code>x</code> such that <code>start <= x < end</code>.</p>
<p>Implement the <code>MyCalendarTwo</code> class:</p>
<ul>
<li><code>MyCalendarTwo()</code> Initializes the calendar object.</li>
<li><code>boolean book(int start, int end)</code> Returns <code>true</code> if the event can be added to the calendar successfully without causing a <strong>triple booking</strong>. Otherwise, return <code>false</code> and do not add the event to the calendar.</li>
MyCalendarTwo myCalendarTwo = new MyCalendarTwo();
myCalendarTwo.book(10, 20); // return True, The event can be booked.
myCalendarTwo.book(50, 60); // return True, The event can be booked.
myCalendarTwo.book(10, 40); // return True, The event can be double booked.
myCalendarTwo.book(5, 15); // return False, The event cannot be booked, because it would result in a triple booking.
myCalendarTwo.book(5, 10); // return True, The event can be booked, as it does not use time 10 which is already double booked.
myCalendarTwo.book(25, 55); // return True, The event can be booked, as the time in [25, 40) will be double booked with the third event, the time [40, 50) will be single booked, and the time [50, 55) will be double booked with the second event.
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<p> </p>
<p><strong>Constraints:</strong></p>
<ul>
<li><code>0 <= start < end <= 10<sup>9</sup></code></li>
<li>At most <code>1000</code> calls will be made to <code>book</code>.</li>