729. My Calendar I

Description

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 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 MyCalendar class:

MyCalendar() 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 double booking. Otherwise, return false and do not add the event to the calendar.

Example 1:

Input
["MyCalendar", "book", "book", "book"]
[[], [10, 20], [15, 25], [20, 30]]
Output
[null, true, false, true]

Explanation
MyCalendar myCalendar = new MyCalendar();
myCalendar.book(10, 20); // return True
myCalendar.book(15, 25); // return False, It can not be booked because time 15 is already booked by another event.
myCalendar.book(20, 30); // return True, The event can be booked, as the first event takes every time less than 20, but not including 20.

Constraints:

0 <= start < end <= 10⁹
At most 1000 calls will be made to book.

Solution

my-calendar-i.py

from sortedcontainers import SortedList

class MyCalendar:

    def __init__(self):
        self.sl = SortedList([(float('-inf'), float('-inf')), (float('inf'), float('inf'))])

    def book(self, start: int, end: int) -> bool:
        index = self.sl.bisect_left((start, end))

        if start < self.sl[index - 1][1] or end > self.sl[index][0]: return False

        self.sl.add((start, end))    
        return True


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