My calendar I

Time: O(NLogN); Space: O(N); medium

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(start, 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: cal = MyCalendar() cal.book(start, end)

Example 1:

Input/Output:

cal = MyCalendar() cal.book(10, 20) # returns True cal.book(15, 25) # returns False cal.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.

Notes:

  • 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].

[1]:

class Node(object):
    """
    Time:  O(NLogN) on average, O(N^2) on worst case
    Space: O(N)
    """
    def __init__(self, start, end):
        self.__start = start
        self.__end = end
        self.__left = None
        self.__right = None

    def insert(self, node):
        if node.__start >= self.__end:
            if not self.__right:
                self.__right = node
                return True
            return self.__right.insert(node)
        elif node.__end <= self.__start:
            if not self.__left:
                self.__left = node
                return True
            return self.__left.insert(node)
        else:
            return False

class MyCalendar1(object):
    def __init__(self):
        self.__root = None

    def book(self, start, end):
        """
        :type start: int
        :type end: int
        :rtype: bool
        """
        if self.__root is None:
            self.__root = Node(start, end)
            return True
        return self.__root.insert(Node(start, end))

[2]:

c = MyCalendar1()
assert c.book(10, 20) == True
assert c.book(15, 25) == False
assert c.book(20, 30) == True

[3]:

class MyCalendar2(object):
    """
    Time:  O(N^2)
    Space: O(N)
    """
    def __init__(self):
        self.__calendar = []

    def book(self, start, end):
        """
        :type start: int
        :type end: int
        :rtype: bool
        """
        for i, j in self.__calendar:
            if start < j and end > i:
                return False
        self.__calendar.append((start, end))
        return True

[4]:

c = MyCalendar2()
assert c.book(10, 20) == True
assert c.book(15, 25) == False
assert c.book(20, 30) == True