729. My Calendar I

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.

class MyCalendar {
    List<int[]> ca;
    public MyCalendar() {
        ca = new ArrayList();
    }
    
    public boolean book(int start, int end) {
        for(int[] arr: ca) {
            if(arr[0] < end && start < arr[1]) return false;
        }
        ca.add(new int[]{start, end});
        return true;
    }
}

O(n^2), O(n)

 

class MyCalendar {

    TreeMap<Integer, Integer> map;
    public MyCalendar() {
        map = new TreeMap();
    }
    
    public boolean book(int start, int end) {
        Integer floor = map.floorKey(start);
        if(floor != null && map.get(floor) > start) return false;
        Integer ceil = map.ceilingKey(start);
        if(ceil != null && ceil < end) return false;
        map.put(start, end);
        return true;
    }
}

floorKey: the closest <= key

ceilingKey: the closest >= key

O(n), O(n)

 

标签：return,start,book,end,Calendar,My,event,MyCalendar,729
来源： https://www.cnblogs.com/wentiliangkaihua/p/16546674.html