729.MyCalendarI.py

'''
    Implement a MyCalendar class to store your events. A new 
    event can be added if adding the event will not cause a 
    double booking.

    Your class will have the method, book(int start, int end). 
    Formally, this represents a booking on the half open 
    interval [start, end), the range of real numbers x such 
    that start <= x < end.

    A double booking happens when two events have some 
    non-empty intersection (ie., there is some time that is 
    common to both events.)

    For each call to the method MyCalendar.book, return 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.
    Your class will be called like this: 
    MyCalendar cal = new MyCalendar(); MyCalendar.book(start, end)

    Example:
    MyCalendar();
    MyCalendar.book(10, 20); // returns true
    MyCalendar.book(15, 25); // returns false
    MyCalendar.book(20, 30); // returns true
    Explanation: 
                The first event can be booked.  The second 
                can't because time 15 is already booked by 
                another event.
                The third event can be booked, as the first 
                event takes every time less than 20, but not 
                including 20.

    Note:
        - The number of calls to MyCalendar.book per test 
          case will be at most 1000.
        - In calls to MyCalendar.book(start, end), start and 
          end are integers in the range [0, 10^9].
'''
#Difficulty: Medium
#108 / 108 test cases passed.
#Runtime: 536 ms
#Memory Usage: 14.9 MB

#Runtime: 536 ms, faster than 38.93% of Python3 online submissions for My Calendar I.
#Memory Usage: 14.9 MB, less than 58.29% of Python3 online submissions for My Calendar I.

class MyCalendar:

    def __init__(self):
        self.schedule = {'start': -1, 'end': -1, 'next': {'start': float(inf), 'end': float(inf)}}

    def book(self, start: int, end: int) -> bool:
        current = self.schedule
        while current['start'] < start:
            prev, current = current, current['next']
        if current['start'] < end or prev['end'] > start:
            return False
        prev['next'] = {'start': start, 'end': end, 'next': current}
        return True


# Your MyCalendar object will be instantiated and called as such:
# obj = MyCalendar()
# param_1 = obj.book(start,end)