729. My Calendar I

https://leetcode.com/problems/my-calendar-i/

注意这道题只需要检查最接近的两个时间就可以了(floorKey + ceilingKey)，它只能保存不重叠的event所以不会出现一个事情开始得早结束得晚的，因为这样会跟最接近的两个重叠。

class MyCalendar {
    private TreeMap<Integer, Integer> map = new TreeMap<>();
    public MyCalendar() {
        
    }
    
    public boolean book(int start, int end) {
        Integer prev = map.floorKey(start);
        Integer next = map.ceilingKey(start);
        if ((prev == null || map.get(prev) <= start) && (next == null || next >= end)) {
            map.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);
 */