Formatted question description: https://leetcode.ca/all/729.html

Medium

Description

Implement a MyCalendar class to store your events. A new event can be added if adding the event will not cause a double booking.

Your class will have the 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 double booking happens when two events have some non-empty intersection (ie., there is some time that is common to both events.)

For each call to the method MyCalendar.book, return 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.

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

Example 1:

MyCalendar();
MyCalendar.book(10, 20); // returns true
MyCalendar.book(15, 25); // returns false
MyCalendar.book(20, 30); // returns true
Explanation:
The first event can be booked.  The second can't because time 15 is already booked by another event.
The third event can be booked, as the first event takes every time less than 20, but not including 20.


Note:

• The number of calls to MyCalendar.book per test case will be at most 1000.
• In calls to MyCalendar.book(start, end), start and end are integers in the range [0, 10^9].

Solution

Use a list to store the intervals of booking, which contains all intervals in sorted order. Each time book(int start, int end) is called, loop over the list of intervals to see whether the new interval [start, end) can be added.

If the new interval can be added at the start or at the end without causing a double booking, add the new interval at the start or at the end and return true.

If the new interval can be added between two intervals without causing a double booking, add the new interval between the two intervals and return true.

If the new interval has intersection with any interval in the list, then adding the interval will cause double booking, so return false.

• import java.util.TreeMap;

public class My_Calendar_I {

public static void main (String[] args) {
My_Calendar_I out = new My_Calendar_I();
MyCalendar c = out.new MyCalendar();

//        System.out.println(c.book(20,29));
//        System.out.println(c.book(13,22));
//        System.out.println(c.book(44,50));
//        System.out.println(c.book(1,7));
//        System.out.println(c.book(2,10));
//        System.out.println(c.book(14,20));
//        System.out.println(c.book(19,25));
//        System.out.println(c.book(36,42));
//        System.out.println(c.book(45,50));

System.out.println(c.book(0,6));
System.out.println(c.book(0,7));

// test on TreeMap
TreeMap<Integer, Integer> tm = new TreeMap<>();
tm.put(3, 10);
tm.put(5, 110);
tm.put(7, 150);
System.out.println(tm.ceilingKey(4)); // output: 5
System.out.println(tm.floorKey(4)); // output: 3
System.out.println(tm.floorKey(1)); // output: null
// @memorize: cannot use int, should use Integer
int floor = tm.floorKey(1);
System.out.println(floor); // output: java.lang.NullPointerException
}

// ref: https://leetcode.com/problems/my-calendar-i/solution/
//      https://leetcode.com/articles/my-calendar-i/
class MyCalendar {

// each element is start->end pair
TreeMap<Integer, Integer> startEndMap;

public MyCalendar() {
startEndMap = new TreeMap<>();
}

public boolean book(int start, int end) {

// Returns the greatest key less than or equal to the given key, or null
Integer prevStart = startEndMap.floorKey(start); // @note: Integer, not int, for later null check

// Returns the least key greater than or equal to the given key, or null
Integer nextStart = startEndMap.ceilingKey(start);

if (
(prevStart == null || startEndMap.get(prevStart) <= start) // get will return end date
&& (nextStart == null || end <= nextStart)
) {
startEndMap.put(start, end);
return true;
}

return false;
}
}

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

}

############

import java.util.Map;
import java.util.TreeMap;

class MyCalendar {

private final TreeMap<Integer, Integer> tm = new TreeMap<>();

public MyCalendar() {
}

public boolean book(int start, int end) {
Map.Entry<Integer, Integer> ent = tm.floorEntry(start);
if (ent != null && ent.getValue() > start) {
return false;
}
ent = tm.ceilingEntry(start);
if (ent != null && ent.getKey() < end) {
return false;
}
tm.put(start, end);
return true;
}
}

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


• // OJ: https://leetcode.com/problems/my-calendar-i/
// Time:
//      MyCalendar: O(1)
//      book: O(logN)
// Space: O(N)
class MyCalendar {
map<int, int> m;
public:
MyCalendar() {}
bool book(int start, int end) {
if (m.empty()) {
m[start] = end;
return true;
}
auto it = m.upper_bound(start);
if (it != m.begin() && prev(it)->second > start) return false;
if (it != m.end() && it->first < end) return false;
m[start] = end;
return true;
}
};

• '''
>>> sd
SortedDict({'a': 111, 'b': 222, 'c': 333})
>>> sd.keys()
SortedKeysView(SortedDict({'a': 111, 'b': 222, 'c': 333}))
>>> sd.values()
SortedValuesView(SortedDict({'a': 111, 'b': 222, 'c': 333}))
>>> sd.items()
SortedItemsView(SortedDict({'a': 111, 'b': 222, 'c': 333}))
>>>
>>>
>>> sd.keys()[1]
'b'
>>> sd.values()[1]
222

>>> sd.append({'aaa':111})
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
AttributeError: 'SortedDict' object has no attribute 'append'
>>>
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
AttributeError: 'SortedDict' object has no attribute 'add'
'''

from sortedcontainers import SortedDict

class MyCalendar:
def __init__(self):
self.sd = SortedDict()

def book(self, start: int, end: int) -> bool:
# bisect_left will not work, due to duplicates
# eg: [[],[10,20],[15,25],[20,30]]
idx = self.sd.bisect_right(start)

# self.sd.keys()[idx] ==> end time
# self.sd.values()[idx] ==> it's start time
if idx < len(self.sd) and end > self.sd.values()[idx]:
return False
self.sd[end] = start
return True

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

############

class Node(object): # double linked list, full scan
def __init__(self, s, e):
self.s = s
self.e = e
self.left = None
self.right = None

class MyCalendar(object):

def __init__(self):
self.root = None

def book_helper(self, s, e, node):
if node.e <= s:
if node.right:
return self.book_helper(s, e, node.right)
else:
node.right = Node(s, e)
return True
elif node.s >= e:
if node.left:
return self.book_helper(s, e, node.left)
else:
node.left = Node(s, e)
return True
else:
return False

def book(self, start, end):
"""
:type start: int
:type end: int
:rtype: bool
"""
if not self.root:
self.root = Node(start, end)
return True
else:
return self.book_helper(start, end, self.root)

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

• type MyCalendar struct {
rbt *redblacktree.Tree
}

func Constructor() MyCalendar {
return MyCalendar{
rbt: redblacktree.NewWithIntComparator(),
}
}

func (this *MyCalendar) Book(start int, end int) bool {
if p, ok := this.rbt.Floor(start); ok && p.Value.(int) > start {
return false
}
if p, ok := this.rbt.Ceiling(start); ok && p.Key.(int) < end {
return false
}
this.rbt.Put(start, end)
return true
}

/**
* Your MyCalendar object will be instantiated and called as such:
* obj := Constructor();
* param_1 := obj.Book(start,end);
*/


• class MyCalendar {
private calendar: number[][];

constructor() {
this.calendar = [];
}

book(start: number, end: number): boolean {
for (const item of this.calendar) {
if (end <= item[0] || item[1] <= start) {
continue;
}
return false;
}
this.calendar.push([start, end]);
return true;
}
}

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


• use std::collections::BTreeMap;

struct MyCalendar {
bt: BTreeMap<i32, i32>,
}

/**
* &self means the method takes an immutable reference.
* If you need a mutable reference, change it to &mut self instead.
*/
impl MyCalendar {
fn new() -> Self {
MyCalendar {
bt: BTreeMap::new(),
}
}

fn book(&mut self, start: i32, end: i32) -> bool {
if let Some((_, &val)) = self.bt.range(..=start).last() {
println!("{} {} {}", start, end, val);
if val > start {
return false;
}
}
if let Some((&key, _)) = self.bt.range(start..).next() {
if key < end {
return false;
}
}
self.bt.insert(start, end);
true
}
}

/**
* Your MyCalendar object will be instantiated and called as such:
* let obj = MyCalendar::new();
* let ret_1: bool = obj.book(start, end);
*/