My Calendar III——LeetCode⑪

//原题链接https://leetcode.com/problems/my-calendar-iii/submissions/

• 题目描述

  Implement a MyCalendarThree class to store your events. A new event can always be added.

  Your class will have one 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 K-booking happens when K events have some non-empty intersection (ie., there is some time that is common to all K events.)

  For each call to the method MyCalendar.book, return an integer K representing the largest integer such that there exists a K-booking in the calendar.

  Your class will be called like this: MyCalendarThree cal = new MyCalendarThree(); MyCalendarThree.book(start, end)

  Example 1:

  MyCalendarThree();
  MyCalendarThree.book(10, 20); // returns 1
  MyCalendarThree.book(50, 60); // returns 1
  MyCalendarThree.book(10, 40); // returns 2
  MyCalendarThree.book(5, 15); // returns 3
  MyCalendarThree.book(5, 10); // returns 3
  MyCalendarThree.book(25, 55); // returns 3
  Explanation:
  The first two events can be booked and are disjoint, so the maximum K-booking is a 1-booking.
  The third event [10, 40) intersects the first event, and the maximum K-booking is a 2-booking.
  The remaining events cause the maximum K-booking to be only a 3-booking.
  Note that the last event locally causes a 2-booking, but the answer is still 3 because
  eg. [10, 20), [10, 40), and [5, 15) are still triple booked.
  

  Note:
  The number of calls to MyCalendarThree.book per test case will be at most 400.
  In calls to MyCalendarThree.book(start, end), start and end are integers in the range [0, 10^9].

• 思路分析
  每次向时间轴里插入一个有向线段，返回此时最多的重合次数

  class MyCalendarThree {
      TreeMap<Integer,Integer> timeline = new TreeMap<Integer,Integer>();
  
      public MyCalendarThree() {
  
      }
  
      public int book(int start, int end) {
          timeline.put(start,timeline.containsKey(start) ? timeline.get(start)+1 : 1);
          timeline.put(end,timeline.containsKey(end) ? timeline.get(end)-1 :-1);
  
          int result = 0,cur = 0;
          for(int i:timeline.values()){
              result = Math.max(result,cur=cur+i);
          }
  
          return result;
      }
  }
  
  /**
   * Your MyCalendarThree object will be instantiated and called as such:
   * MyCalendarThree obj = new MyCalendarThree();
   * int param_1 = obj.book(start,end);
   */