Leetcode_729. My Calendar I

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 trueMyCalendar.book(15, 25); // returns falseMyCalendar.book(20, 30); // returns trueExplanation: 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].

由于start and end are integers in the range [0, 10^9]. 所以不能用数组

可以用TreeMap 中的方法：

    1 . floorKey（）返回小于或者等于给定键的最大键，如果不存在返回null;

    2 . ceilingKey() 返回大于等于给定键的最小值，如果不存在返回null；

思路： 1.用floorKey（start） 获取 最靠近的start 左边的key1   根据key1的value（end）大于start 则交叉 返回false

            2. 用ceilingKey()  获取 最靠近的start 右边的key2  根据key 小于 start的end 则交叉 返回 false

class MyCalendar {    TreeMap<Integer, Integer> map;    public MyCalendar() {        map = new TreeMap<>();    }    public boolean book(int start, int end) {        Integer floorKey = map.floorKey(start);        if (floorKey != null && map.get(floorKey) > start)    return false;        Integer ceilingKey = map.ceilingKey(start);        if (ceilingKey != null && ceilingKey < end) return false;        map.put(start, end);        return true;    }}

参考： https://discuss.leetcode.com/topic/111205/java-8-liner-treemap