my-calendar-ii.js

/**
 * My Calendar II
 *
 * Implement a MyCalendarTwo class to store your events. A new event can be added if adding
 * the event will not cause a triple booking.
 *
 * Your class will have one 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 triple booking happens when three events have some non-empty intersection (ie., there is some
 * time that is common to all 3 events.)
 *
 * For each call to the method MyCalendar.book, return true if the event can be added to the calendar
 * successfully without causing a triple 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 true
 * MyCalendar.book(50, 60); // returns true
 * MyCalendar.book(10, 40); // returns true
 * MyCalendar.book(5, 15);  // returns false
 * MyCalendar.book(5, 10);  // returns true
 * MyCalendar.book(25, 55); // returns true
 *
 * Explanation:
 *
 * The first two events can be booked.  The third event can be double booked.
 * The fourth event (5, 15) can't be booked, because it would result in a triple booking.
 * The fifth event (5, 10) can be booked, as it does not use time 10 which is already double booked.
 * The sixth event (25, 55) can be booked, as the time in [25, 40) will be double booked with the third event;
 * the time [40, 50) will be single booked, and the time [50, 55) will be double booked with the second event.
 *
 * 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].
 */

class MyCalendarTwo {
  constructor() {
    this.calendar = [];
    this.overlaps = [];
  }

  /**
   * @param {number} start
   * @param {number} end
   * @return {boolean}
   */
  book(start, end) {
    for (let interval of this.overlaps) {
      if (interval[0] < end && start < interval[1]) {
        return false;
      }
    }

    for (let interval of this.calendar) {
      if (interval[0] < end && start < interval[1]) {
        this.overlaps.push([Math.max(start, interval[0]), Math.min(end, interval[1])]);
      }
    }

    this.calendar.push([start, end]);

    return true;
  }
}

export { MyCalendarTwo };