using System;
/*
This program determines the day of the week for January 1st of a given year.
Approach:
---------
C# provides built‑in date/time handling through the DateTime struct:
- new DateTime(year, month, day) : constructs a calendar date
- DateTime.DayOfWeek : returns a DayOfWeek enum value
DayOfWeek values:
Sunday, Monday, Tuesday, Wednesday,
Thursday, Friday, Saturday
This avoids manual calendar arithmetic and uses efficient built‑in routines.
*/
class Program
{
// Convert DayOfWeek enum to a readable string (e.g., "Thursday")
static string WeekdayName(DayOfWeek dow)
{
string s = dow.ToString();
return char.ToUpper(s[0]) + s.Substring(1).ToLower();
}
// Compute weekday of January 1st for a given year
static string Jan1Weekday(int year)
{
DateTime dateValue = new DateTime(year, 1, 1); // January 1st of given year
DayOfWeek dow = dateValue.DayOfWeek; // Built‑in weekday computation
return WeekdayName(dow);
}
static void Main()
{
int year = 2026;
string resultStr = Jan1Weekday(year);
Console.WriteLine($"January 1st, {year} falls on a {resultStr}.");
}
}
/*
run:
January 1st, 2026 falls on a Thursday.
*/
