UVa 893 - Y3K Problem

Accepted date: 2014-01-24
Ranking (as of 2014-01-24): 214 out of 585
Language: C++

/*
  UVa 893 - Y3K Problem

  To build using Visual Studio 2012:
    cl -EHsc -O2 UVa_893_Y3K_Problem.cpp
*/

#include <iostream>
using namespace std;

inline bool is_leap_year(int year)
{
  if (!(year % 400))
    return true;
  else if (!(year % 100))
    return false;
  else if (!(year % 4))
    return true;
  else
    return false;
}

// return the number of days of given year
int get_number_of_days(int year)
{
  return (is_leap_year(year)) ? 366 : 365;
}

// return the number of days from the first day of given year
int get_number_of_days(int year, int month, int day)
{
  const int nr_days[] =
    {0, 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334};
    // nr_days[i] is the number of days before the first day of i-th month
  const int nr_days_leap_year[] =
    {0, 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335};
    // nr_days[i] is the number of days before the first day of i-th month
    // for leap years
  int nd = day;
  nd += (is_leap_year(year)) ? nr_days_leap_year[month] : nr_days[month];
  return nd;
}

// return the month and day from the number of days of given year
void get_month_day(int year, int nr_days, int& month, int& day)
{
  const int nr_month_days[] =
    {0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365};
    // nr_month_days[i] is the number of days up to i-th month
  const int nr_month_days_leap_year[] =
    {0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366};
    // nr_month_days[i] is the number of days up to i-th month for leap years
  const int* month_days = (is_leap_year(year)) ?
    nr_month_days_leap_year : nr_month_days;
  for (month = 1; ; month++)
    if (month_days[month] >= nr_days)
      break;
  day = nr_days - month_days[month - 1];
}

int main()
{
  while (true) {
    int n, d, m, y;
    cin >> n >> d >> m >> y;
    if (!n && !d && !m && !y)
      break;
    n += get_number_of_days(y, m, d);
    for (int nd = get_number_of_days(y); n > nd; nd = get_number_of_days(++y))
      n -= nd;
    get_month_day(y, n, m, d);
    cout << d << ' ' << m << ' ' << y << endl;
  }
  return 0;
}