Solution to Problem 19

Author: daniel-s-ingram

Project Euler/Problem 19/sol1.py

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+from __future__ import print_function
+'''
+Counting Sundays
+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)?
+'''
+
+days_per_month = [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]
+
+day = 6
+month = 1
+year = 1901
+
+sundays = 0
+
+while year < 2001:
+	day += 7
+
+	if (year%4 == 0 and not year%100 == 0) or (year%400 == 0):
+		if day > days_per_month[month-1] and month is not 2:
+			month += 1
+			day = day-days_per_month[month-2]
+		elif day > 29 and month is 2:
+			month += 1
+			day = day-29
+	else:
+		if day > days_per_month[month-1]:
+			month += 1
+			day = day-days_per_month[month-2]
+	
+	if month > 12:
+		year += 1
+		month = 1
+
+	if year < 2001 and day is 1:
+		sundays += 1
+
+print(sundays)