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Missed Classes

Description

Your Math teacher takes education very seriously, and hates it when a class is missed or canceled for any reason. He even made up the following rule: if a class is missed because of a holiday, the teacher will compensate for it with a makeup class after school.

You’re given an array, daysOfTheWeek, with the weekdays on which your teacher’s classes are scheduled, and holidays, representing the dates of the holidays throughout the academic year (from 1st of September in year to 31st of May in year + 1). How many times will you be forced to stay after school for a makeup class because of holiday conflicts in the current academic year?

For your convenience, here is the list of month lengths (from January to December, respectively):

  • Month lengths: 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31.

Please, note that in leap years February has 29 days.

Note (leap years): Year is leap if its number is divisible by 4 and isn’t divisible by 100 or if its number is divisible by 400.

Example

For year = 2015, daysOfTheWeek = [2, 3], and holidays = ["11-04", "02-22", "02-23", "03-07", "03-08", "05-09"], the output should be missedClasses(year, daysOfTheWeek, holidays) = 3.

November 4th of 2015 is a Wednesday, February 23th of 2016 and March 8th of 2016</sup> are Tuesdays, and the other holidays fall on Mondays. Classes are scheduled on Wednesdays and Tuesdays, so there will be only 3 missed classes.

Input/Output

  • [execution time limit] 4 seconds (js)

  • [input] integer year

    An integer representing the correct year. The current academic year started on September 1st and will finish on May 31st of year + 1.

    Guaranteed constraints:
    1900 ≤ year ≤ 2100.

  • [input] array.integer daysOfTheWeek

    A sorted array of integers from 1 to 7 representing the days of the week (1-based, i.e. 1 for Monday, 2 for Tuesday and so on) on which classes are scheduled.

    Guaranteed constraints:
    0 ≤ daysOfTheWeek.length ≤ 7,
    1 ≤ daysOfTheWeek[i] ≤ 7.

  • [input] array.string holidays

    An array of strings representing the correct dates of holidays in this academic year in the format "mm-dd", where "mm" stands for the month (1-based, i.e. "01" for January, "02" for February and so on) and "dd" stands for the day.

    Guaranteed constraints:
    0 ≤ holidays.length ≤ 30,
    1 ≤ int(mm) ≤ 12, except 6, 7 and 8,
    1 ≤ int(dd) ≤ 31.

  • [output] integer

    • The number of classes that will be missed.

[JavaScript (ES6)] Syntax Tips

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// Prints help message to the console
// Returns a string
function helloWorld(name) {
console.log("This prints to the console when you Run Tests");
return "Hello, " + name;
}

Solution

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function missedClasses(year, daysOfTheWeek, holidays) {
  var date = new Date();
  daysOfTheWeek = daysOfTheWeek.map((d) => d % 7);
  var makeUpDays = 0;
  for (var i = 0; i < holidays.length; i++) {
    if (Number(holidays[i].split("-")[0]) >= 9) {
      date.setTime(Date.parse(holidays[i] + "-" + year));
    } else {
      date.setTime(Date.parse(holidays[i] + "-" + (year + 1)));
    }
    if (daysOfTheWeek.includes(date.getDay())) {
      makeUpDays++;
    }
  }
  return makeUpDays;
}