projecteuler19

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:

#include "stdafx.h" #include <iostream> using namespace std; enum DayPastTable{ JAN = 31, FEB = 28, MARCH = 31, APRIL = 30, MAY = 31, JUNE = 30, JULY = 31,AUG = 31, SEPT=30, OCT = 31, NOV=30,DEC=31 }; enum Day{ MON= 0,TUE,WED,THU,FRI,SAT,SUN }; int DayPastTable[]={ 0, 0,31,59,//JAN,FEB,MARCH 90,120,151, 181,212,243, 273,304,334 }; bool IsLeapYear(int year) { return (year % 400 == 0)|((year & 3) == 0 && (year % 100 !=0)); } int GetDays(int month, int year,int date = 1) { int days = (year - 1900) *365 + DayPastTable[month]; int PastLeapYears = (year - 1 - 1900) / 4; if(PastLeapYears > 0) days += PastLeapYears; if(month > 2 &&IsLeapYear(year)) { days +=1; } days += date - 1; return days; } int GetDayOfFirstDate(int month, int year) { return GetDays(month,year) % 7; } int _tmain(int argc, _TCHAR* argv[]) { int count = 0; cout << " 1900 is leap year?"<< IsLeapYear(1900) << endl; cout << " 01/03/1900 " << GetDays(3,1900) << " from begin " << endl; cout << "01/01/1900 is " << GetDayOfFirstDate(1,1900) << endl; cout << "01/02/1900 is " << GetDayOfFirstDate(2,1900) << endl; cout << "01/01/1901 is " << GetDayOfFirstDate(1,1901) << endl; cout << "01/05/2009 is " << GetDayOfFirstDate(5,2009) << endl; cout << "01/02/2000 is " << GetDayOfFirstDate(2,2000) << endl; cout << "01/03/2000 is " << GetDayOfFirstDate(3,2000) << endl; cout << "01/02/2004 is " << GetDayOfFirstDate(2,2004) << endl; cout << "01/03/2004 is " << GetDayOfFirstDate(3,2004) << endl; for(int year = 1901; year <=2000; year++) { for(int month = 1; month <13; month++) { if(GetDayOfFirstDate(month,year) == Day::SUN) { cout << month << "/" << year<< ","; count++; if(count % 10 ==0) { cout << endl; } } } } cout << count << endl; system("pause"); return 0; }