Adv2018/D4.2/Program.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text.RegularExpressions;

namespace D4._2
{
    class Program
    {
        static void Main(string[] args)
        {
            if (args.Length < 1) return;
            if (File.Exists(args[0]) == false) return;

            var dic = new Dictionary<DateTime, string>();
            var guard = new Dictionary<string, Dictionary<int, int>>();

            var file = File.OpenText(args[0]);

            var regex = new Regex(@"\[(.*)\]");

            do
            {
                var line = file.ReadLine();
                if (line == null) break;

                var dateStr = line.Substring(0, 18).Trim('[', ']');
                var date = DateTime.Parse(dateStr);

                dic.Add(date, line.Substring(19, line.Length - 19));
            } while (true);

            var ordered = dic.OrderBy(kvp => kvp.Key);

            string curGuard = string.Empty;
            DateTime asleep = DateTime.Now;
            foreach (var kvp in ordered)
            {
                var date = kvp.Key;
                var str = kvp.Value;

                if (str.StartsWith("Guard")) curGuard = str.Split(' ')[1];
                {
                    if (guard.ContainsKey(curGuard) == false)
                    {
                        var d = new Dictionary<int, int>();
                        for (var i = 0; i < 60; i++) d.Add(i, 0);
                        guard.Add(curGuard, d);
                    }
                }

                if (str == "falls asleep")
                {
                    asleep = date;
                }

                if (str == "wakes up")
                {
                    for (int m = asleep.Minute; m < date.Minute; m++)
                        guard[curGuard][m] += 1;
                }
            }

            KeyValuePair<int, int> highestMinute = new KeyValuePair<int, int>(0, 0);
            string sleeper = "";
            foreach (var g in guard)
            {
                var minute = g.Value.OrderByDescending(v => v.Value).FirstOrDefault();

                if (minute.Value > highestMinute.Value)
                {
                    highestMinute = minute;
                    sleeper = g.Key;
                }
            }
            
            Console.WriteLine($"Guard {sleeper} sleeps {highestMinute.Value} times on {highestMinute.Key}th minute");
            var id = int.Parse(sleeper.TrimStart('#'));
            Console.WriteLine($"Answer : {id * highestMinute.Key}");
        }
    }
}