729. My Calendar I

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 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.

🧠 Thuật Toán & Kỹ Thuật

Binary Search (Tìm kiếm nhị phân)
⏱️ Thời gian O(log n)
💾 Không gian O(n)

💻 Lời Giải

Python 0729-my-calendar-i.py 
from sortedcontainers import SortedList

class MyCalendar:

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

    def book(self, start: int, end: int) -> bool:
        if not self.treeMap:
            self.treeMap.add((end, start))
            return True
            
        i = self.treeMap.bisect_right((start, start))
        
        if i == len(self.treeMap) and self.treeMap[-1][0] <= start:
            self.treeMap.add((end, start))
            return True
        
        if end <= self.treeMap[i][1]:
            self.treeMap.add((end, start))
            return True
        
        return False


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