Algorithm

Problem Name: 731. My Calendar II

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`.

Code Examples

#1 Code Example with Java Programming

```Code - Java Programming```

``````
class MyCalendarTwo {

private TreeMap delta;

public MyCalendarTwo() {
this.delta = new TreeMap < >();
}

public boolean book(int start, int end) {
delta.put(start, delta.getOrDefault(start, 0) + 1);
delta.put(end, delta.getOrDefault(end, 0) - 1);
int active = 0;
for (int d : delta.values()) {
active += d;
if (active >= 3) {
delta.put(start, delta.get(start) - 1);
delta.put(end, delta.get(end) + 1);
return false;
}
}
return true;
}
}
``````
Copy The Code &

Input

cmd
["MyCalendarTwo", "book", "book", "book", "book", "book", "book"] [[], [10, 20], [50, 60], [10, 40], [5, 15], [5, 10], [25, 55]]

Output

cmd
[null, true, true, true, false, true, true]

#2 Code Example with Javascript Programming

```Code - Javascript Programming```

``````
const MyCalendarTwo = function () {
this.calendar = []
this.overlaps = []
}

MyCalendarTwo.prototype.book = function (start, end) {
for (let i = 0; i  <  this.overlaps.length; i++) {
if (start < this.overlaps[i].end && end > this.overlaps[i].start)
return false
}

for (let i = 0; i  <  this.calendar.length; i++) {
if (start < this.calendar[i].end && end > this.calendar[i].start)
this.overlaps.push({
start: Math.max(start, this.calendar[i].start),
end: Math.min(end, this.calendar[i].end),
})
}
this.calendar.push({ start: start, end: end })
return true
}
``````
Copy The Code &

Input

cmd
["MyCalendarTwo", "book", "book", "book", "book", "book", "book"] [[], [10, 20], [50, 60], [10, 40], [5, 15], [5, 10], [25, 55]]

Output

cmd
[null, true, true, true, false, true, true]

#3 Code Example with Python Programming

```Code - Python Programming```

``````
class MyCalendarTwo:
def __init__(self):
self.overlaps = []
self.calendar = []

def book(self, start, end):
for i, j in self.overlaps:
if start < j and end > i:
return False
for i, j in self.calendar:
if start < j and end > i:
self.overlaps.append((max(start, i), min(end, j)))
self.calendar.append((start, end))
return True
``````
Copy The Code &

Input

cmd
["MyCalendarTwo", "book", "book", "book", "book", "book", "book"] [[], [10, 20], [50, 60], [10, 40], [5, 15], [5, 10], [25, 55]]

Output

cmd
[null, true, true, true, false, true, true]