B-Tree

729. My Calendar I

You are implementing a program to use as your calendar. We can add a new event if adding the event will not cause a double booking.

A double booking happens when two events have some non-empty intersection (i.e., some moment is common to both events.).

The event can be represented as a pair of integers startTime and endTime that represents a booking on the half-open interval [startTime, endTime), the range of real numbers x such that startTime <= x < endTime.

Implement the MyCalendar class:

• MyCalendar() Initializes the calendar object.
• boolean book(int startTime, int endTime) Returns true if the event can be added to the calendar successfully without causing a double booking. Otherwise, return false and do not add the event to the calendar.

class MyCalendar {
    TreeMap<Integer, Integer> calendar;

    MyCalendar() {
        this.calendar = new TreeMap();
    }

    public boolean book(int start, int end) {
        // Check for overlapping with previous event
        Integer prev = calendar.floorKey(start);
        if (prev != null && calendar.get(prev) > start) {
            return false;
        }
        // Check for overlapping with next event
        Integer next = calendar.ceilingKey(start);
        if (next != null && end > next) {
            return false;
        }
        calendar.put(start, end);
        return true;
    }
}

/**
 * Your MyCalendar object will be instantiated and called as such:
 * MyCalendar obj = new MyCalendar();
 * boolean param_1 = obj.book(startTime,endTime);
 */