Project Euler Problem 19 Solution

Problem 19: Counting Sundays

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)?

Solution 19: Counting Sundays

static int Problem019Solution()
		{
			//Set intial conditions
			int dayofWeek = 2; 			//1st of Jan 1901 = Tuesday.
			int firstMonthSundays = 0; 		//start count of Sundays that fall on the first of the month.
			for (int i = 1901; i <= 2000; i++) 	//Loop over each year
			{
				for (int j = 1; j <= 12; j++)	//Loop over each month
				{
					Console.WriteLine("i = {0}, j = {1}", i, j);
					int monthDays = NumberOfDays(i, j); 	//Returns number of days, given month and year
					dayofWeek += monthDays % 28;
					if (dayofWeek % 7 == 0)
					{
						firstMonthSundays += 1;
						dayofWeek = 0;
					}
				}
			}
			{ return firstMonthSundays; }
		}
		static int NumberOfDays(int Year, int month)
		{
			int monthDays = 0;
			if (month == 1 || month == 3 || month == 5 || month == 7 || month == 8 || month == 10 || month == 12)
			{
				monthDays = 31;
			}
			if (month == 4 || month == 6 || month == 9 || month == 11)
			{
				monthDays = 30;
			}
			if (month == 2 && Year%4 == 0)
			{
				monthDays = 29;
			}
			if (month == 2)
			{
				monthDays = 28;
			}
			{return monthDays;}
		}