Adv2016/D06.2/Program.cs

using System;
using System.IO;

namespace D6._2
{
    class Program
    {
        static void Main(string[] args)
        {
            if (args.Length < 1) throw new ArgumentException();
            if (File.Exists(args[0]) == false) throw new FileNotFoundException();

            var freq = new int[8][];

            using (var file = File.OpenText(args[0]))
            {
                while (true)
                {
                    var line = file.ReadLine();
                    if (line == null) break;

                    for (var i = 0; i < 8; i++)
                    {
                        if (freq[i] == null) freq[i] = new int[26];
                        freq[i][line[i] - 'a']++;
                    }
                }
            }

            var password = new char[8];

            for (var i = 0; i < 8; i++)
            {
                int min = int.MaxValue, mini = 0;
                for (var ci = 0; ci < 26; ci++)
                {
                    if (freq[i][ci] < min)
                    {
                        mini = ci;
                        min = freq[i][ci];
                    }
                }

                password[i] = (char)(mini + 'a');
            }

            Console.WriteLine($"Password is : {string.Join("", password)}");
        }
    }
}