729. My Calendar I

class MyCalendar {
    
    List<int[]> times;

    public MyCalendar() {
        times = new ArrayList<>();
    }
    
    public boolean book(int start, int end) {
        for (int[] time : times) {
            if (Math.max(start, time[0]) < Math.min(end, time[1])) {
                return false;
            }
        }
        times.add(new int[]{start, end});
        return true;
    }
}

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

class MyCalendar {
    
    TreeMap<Integer, Integer> calendar;

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

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