729. My Calendar I

Question

You are implementing a program to use as your calendar. We can add a new event if adding the event will not cause a double booking.

A double booking happens when two events have some non-empty intersection (i.e., some moment is common to both events.).

The event can be represented as a pair of integers start and end that represents a booking on the half-open interval [start, end), the range of real numbers x such that start <= x < end.

Implement the MyCalendar class:

• MyCalendar() Initializes the calendar object.
• boolean book(int start, int end) Returns 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.

Solution

有更快速的解法，需要用到TreeMap，有时间再研究。

使用一个队列记录已经预定的范围。
添加无穷大到队列中，方便后期计算。

当预定新的时间段时，遍历队列，如果上一个数组的最大值小于start和end且当前遍历数组大于start和end，则可以预定，将当前的数组插入当前位置，并返回true。
如果没有满足条件的，则返回false。

Code

class MyCalendar {
    List<int[]> arr;
    public MyCalendar() {
        arr = new ArrayList<>();
        int[] inf = new int[2];
        inf[0] = Integer.MAX_VALUE;
        inf[1] = Integer.MAX_VALUE;
        arr.add(inf);
    }
    
    public boolean book(int start, int end) {
        int[] last = new int[2];
        for(int i = 0; i < arr.size(); i++){
            int[] curr = arr.get(i);
            if(last[1] < end && last[1] <= start && curr[0] >= end && curr[0] > start){
                int[] n = new int[2];
                n[0] = start;
                n[1] = end;
                arr.add(i, n);
                return true;
            }
            last = curr;
        }
        return false;
    }
}

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