LeetCode #729 - My Calendar I

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本文介绍了一个名为MyCalendar的类的实现，该类用于存储事件并防止重复预订。通过使用C++中的set数据结构，可以有效地检查新事件是否与现有事件冲突，并确保不会发生重叠。文章详细解释了如何判断两个事件是否相交以及如何插入新事件。

题目描述：

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].

class MyCalendar {
public:
    MyCalendar() {}
    
    bool book(int start, int end) {
        if(s.empty()) 
        {
            s.insert({start,end});
            return true;
        }
        else
        {
            pair<int,int> p={start,end};
            set<pair<int,int>>::iterator it=lower_bound(s.begin(),s.end(),p);
            if(it!=s.begin())
            {
                pair<int,int> x=*prev(it);
                if(isIntersect(x,p)) return false;
            }
            if(it!=s.end())
            {
                pair<int,int> x=*it;
                if(isIntersect(x,p)) return false;
            }
            s.insert({start,end});
            return true;
        }
    }
    
    bool isIntersect(pair<int,int> a, pair<int,int> b)
    {
        if(a.second<=b.first||b.second<=a.first) return false;
        else return true;
    }
    
private:
    set<pair<int,int>> s;
};

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