public static GuardEvent Parse(string eventString)
{
var match = new Regex(@"^\[([0-9\- \:]+)\] (wakes up|falls asleep|Guard #[0-9]+ begins shift)$")
.Match(eventString);
var evt = new GuardEvent
{
When = DateTime.ParseExact(match.Groups[1].Value, "yyyy-MM-dd HH:mm", CultureInfo.InvariantCulture)
};
var desc = match.Groups[2].Value;
if (string.Equals(desc, "wakes up", StringComparison.Ordinal))
{
evt.Type = GuardEventType.WakesUp;
evt.GuardId = -1;
}
else if (string.Equals(desc, "falls asleep", StringComparison.Ordinal))
{
evt.Type = GuardEventType.FallsAsleep;
evt.GuardId = -1;
}
else
{
evt.Type = GuardEventType.BeginsShift;
var guardIdMatch = new Regex("^Guard #([0-9]+) begins shift$")
.Match(desc);
evt.GuardId = int.Parse(guardIdMatch.Groups[1].Value);
}
return(evt);
}
static void Main(string[] args)
{
var events = System.IO.File.ReadAllLines("./input.txt")
.Select(o => GuardEvent.Parse(o))
.OrderBy(o => o.When)
.ToList();
var guards = new Dictionary <int, Guard>();
var id = 0;
var fellAsleep = default(DateTime);
foreach (var e in events)
{
if (e.Type == GuardEventType.BeginsShift)
{
id = e.GuardId;
continue;
}
if (e.Type == GuardEventType.FallsAsleep)
{
fellAsleep = e.When;
continue;
}
if (!guards.TryGetValue(id, out var guard))
{
guard = new Guard {
Id = id
};
guards.Add(guard.Id, guard);
}
for (var minute = fellAsleep.Minute; minute < e.When.Minute; minute++)
{
if (!guard.SleepingMinutes.TryGetValue(minute, out int count))
{
count = 0;
}
count++;
guard.SleepingMinutes[minute] = count;
}
}
var guardMostAsleep = guards.Values
.OrderByDescending(o => o.TotalMinutesAsleep)
.First();
Console.WriteLine(
$"Guard #{guardMostAsleep.Id} was asleep the most, and slept most on minute {guardMostAsleep.MinuteMostAsleep}.");
var guardMostAsleepOnSameMinute = (from g in guards.Values
where g.MinuteMostAsleep.HasValue
let minuteMostAsleep = g.MinuteMostAsleep.Value
let timesAsleep = g.SleepingMinutes[minuteMostAsleep]
orderby timesAsleep descending
select new
{
Id = g.Id,
MinuteMostAsleep = minuteMostAsleep,
TimesAsleep = timesAsleep
}).First();
Console.WriteLine(
$"Guard #{guardMostAsleepOnSameMinute.Id} was asleep the most on the same minute, sleeping {guardMostAsleepOnSameMinute.TimesAsleep} times on minute {guardMostAsleepOnSameMinute.MinuteMostAsleep}.");
}