Euler 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)?


In [1]:
import datetime
print (sum(datetime.date(yy, mm, 1).weekday() == 6
          for yy in range(1901, 2001)
          for mm in range(1, 13)))


171

In [ ]: