/**
 * Problem 19 - Counting Sundays
 *
 * @see {@link https://projecteuler.net/problem=19}
 *
 * You are given the following information, but you may prefer to do some research for yourself.
 * 1 Jan 1900 was a Monday.
 * Thirty days has September,
 * April, June and November.
 * All the rest have thirty-one,
 * Saving February alone,
 * Which has twenty-eight, rain or shine.
 * And on leap years, twenty-nine.
 * A leap year occurs on any year evenly divisible by 4, but not on a century unless it is divisible by 400.
 * How many Sundays fell on the first of the month during the twentieth century (1 Jan 1901 to 31 Dec 2000)?
 *
 * @author ddaniel27
 */
import { isLeapYear } from '../Maths/LeapYear'

function problem19() {
  let sundaysCount = 0 // Count of Sundays
  let dayOfWeek = 2 // 1st Jan 1900 was a Monday, so 1st Jan 1901 was a Tuesday

  for (let year = 1901; year