729. My Calendar I

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729. My Calendar I

Description

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 startTime and endTime that represents a booking on the half-open interval [startTime, endTime), the range of real numbers x such that startTime <= x < endTime.

Implement the MyCalendar class:

  • MyCalendar() Initializes the calendar object.
  • boolean book(int startTime, int endTime) 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:

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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 <= 10^9
  • At most 1000 calls will be made to book.

Hints/Notes

Solution

Language: C++

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class MyCalendar {
public:
    set<pair<int, int>> s;

    MyCalendar() {

    }
    // start, it->first, it->second, endTime
    // start,
    bool book(int startTime, int endTime) {
        auto it = s.lower_bound({startTime, endTime});
        if (it != s.end()) {
            auto [next_start, next_end] = *it;
            if (endTime > next_start) {
                return false;
            }
        }
        if (it != s.begin()) {
            auto [prev_start, prev_end] = *prev(it);
            if (prev_end > startTime) {
                return false;
            }
        }
        s.insert({startTime, endTime});
        return true;
    }
};

/**
 * Your MyCalendar object will be instantiated and called as such:
 * MyCalendar* obj = new MyCalendar();
 * bool param_1 = obj->book(startTime,endTime);
 */