Project 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)?

利用现成的函数库神马的最无耻了~~~

def HowManySundaysOnJans():
import datetime
count = 0
for y in range(1901,2001):
for m in range(1,13):
if datetime.datetime(y,m,1).weekday() == 6:
count += 1
return count

我在想一个问题，肯定有种办法根据年月日直接计算任意日期是星期几的。要不然所有和日期相关的软件不都得设置个基准然后慢慢模啊？！百度了一下，果然有个叫做Zeller公式的！

接下来不弄了~