# My Calendar III

This page explains Java solution to problem `My Calendar III` using `TreeMap` data structure.

## Problem Statement

Implement a `MyCalendarIii` 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 `

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.

Example 1:

Input:
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.

Example 2:

Input: A = [1,2], B = [3,4]
Output: 2.50000
Explanation: merged array = [1,2,3,4] and median is (2 + 3) / 2 = 2.5

## Solution

If you have any suggestions in below code, please create a pull request by clicking here.
``````
package com.vc.hard;

import java.util.*;

class MyCalendarIii {
private TreeMap<Integer, Integer> map;
public MyCalendarIii() {
map = new TreeMap<>();
}

public int book(int start, int end) {
map.put(start, map.getOrDefault(start, 0) + 1);
map.put(end, map.getOrDefault(end, 0) - 1);

int ongoing = 0;
int res = 0;
for(Map.Entry<Integer, Integer> entry: map.entrySet()) {
ongoing += entry.getValue();
res = Math.max(ongoing, res);
}
return res;
}
}

/**
* Your MyCalendarThree object will be instantiated and called as such:
* MyCalendarIii obj = new MyCalendarIii();
* int param_1 = obj.book(start,end);
*/
``````

## Time Complexity

O(N2) Where
N is total number of bookings

## Space Complexity

O(N) Where
N is total number of bookings