731. My Calendar II

Medium (Trung bình) Python 🔗 Xem trên LeetCode

📋 Đề Bài

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

A triple booking happens when three events have some non-empty intersection (i.e., some moment is common to all the three 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 MyCalendarTwo class:

  • MyCalendarTwo() 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 triple booking. Otherwise, return false and do not add the event to the calendar.

 

Example 1:

Input
["MyCalendarTwo", "book", "book", "book", "book", "book", "book"]
[[], [10, 20], [50, 60], [10, 40], [5, 15], [5, 10], [25, 55]]
Output
[null, true, true, true, false, true, true]

Explanation
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.

 

Constraints:

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

💻 Lời Giải

Python 0731-my-calendar-ii.py 
from sortedcontainers import SortedList

class MyCalendarTwo:

    def __init__(self):
        self.line = SortedList()

    def book(self, start: int, end: int) -> bool:
        self.line.add((start, 1))
        self.line.add((end, -1))
        
        group = 0
        ans = True
        
        for element in self.line:
            group += element[1]
            if group == 3:
                ans = False
                break
        
        if not ans:
            self.line.discard((start, 1))
            self.line.discard((end, -1))
            
        return ans


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