MyCalendarThree.java

package leetcode.algo.misc.leet_zh_732;

import java.util.TreeMap;

public class MyCalendarThree {

    /*
     * 732. My Calendar III
     * 执行用时 : 353 ms
     * 内存消耗 : 55.5 MB
     * */
    private TreeMap<Integer, Integer> calendar;

    public MyCalendarThree() {
        calendar = new TreeMap<>();
    }

    public int book(int start, int end) {

        // 添加至日程中
        calendar.put(start, calendar.getOrDefault(start, 0) + 1);
        calendar.put(end, calendar.getOrDefault(end, 0) - 1);

        // 记录最大活跃的日程数
        int max = 0;
        // 记录活跃的日程数
        int active = 0;

        for (Integer d : calendar.values()) {
            // 以时间线统计日程
            active += d;

            // 找到活跃事件数量最多的时刻，记录下来。
            if (active > max) {
                max = active;
            }
        }

        return max;
    }

    public static void main(String[] args) {
        MyCalendarThree myCalendar = new MyCalendarThree();
        System.out.println(myCalendar.book(10, 20));
        System.out.println(myCalendar.book(50, 60));
        System.out.println(myCalendar.book(10, 40));
        System.out.println(myCalendar.book(5, 15));
        System.out.println(myCalendar.book(25, 55));
    }
}