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TrustPilotChallenge/dotnet/WhiteRabbit/Program.cs

170 lines
5.7 KiB

namespace WhiteRabbit
{
using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Configuration;
using System.Diagnostics;
using System.Linq;
using System.Numerics;
using System.Text;
/// <summary>
/// Main class
/// </summary>
public static class Program
{
/// <summary>
/// Main entry point
/// </summary>
public static void Main()
{
var stopwatch = new Stopwatch();
stopwatch.Start();
var sourcePhrase = ConfigurationManager.AppSettings["SourcePhrase"];
var sourceChars = ToOrderedChars(sourcePhrase);
var maxWordsInPhrase = int.Parse(ConfigurationManager.AppSettings["MaxWordsInPhrase"]);
if (sourceChars.Length + maxWordsInPhrase > 27)
{
Console.WriteLine("Only anagrams of up to 27 characters are allowed");
return;
}
if (!BitConverter.IsLittleEndian)
{
Console.WriteLine("Only little-endian systems are supported due to MD5Digest optimizations");
return;
}
if (IntPtr.Size != 8)
{
Console.WriteLine("Only 64-bit systems are supported due to MD5Digest optimizations");
return;
}
if (Vector<uint>.Count != 4)
{
Console.WriteLine("Only 128-bit SSE systems are supported due to MD5Digest optimizations");
}
var expectedHashesAsVectors = ConfigurationManager.AppSettings["ExpectedHashes"]
.Split(',')
.Select(hash => new Vector<uint>(HexadecimalStringToUnsignedIntArray(hash)))
.ToArray();
#if DEBUG
var anagramsBag = new ConcurrentBag<string>();
#endif
var processor = new StringsProcessor(
Encoding.ASCII.GetBytes(sourcePhrase),
maxWordsInPhrase,
ReadInput());
Console.WriteLine($"Initialization complete; time from start: {stopwatch.Elapsed}");
stopwatch.Restart();
processor.GeneratePhrases()
.ForAll(phraseBytes =>
{
Debug.Assert(
sourceChars == ToOrderedChars(ToString(phraseBytes)),
$"StringsProcessor produced incorrect anagram: {ToString(phraseBytes)}");
var hashVector = ComputeHashVector(phraseBytes);
if (Array.IndexOf(expectedHashesAsVectors, hashVector) >= 0)
{
var phrase = ToString(phraseBytes);
var hash = VectorToHexadecimalString(hashVector);
Console.WriteLine($"Found phrase for {hash}: {phrase}; time from start is {stopwatch.Elapsed}");
}
#if DEBUG
anagramsBag.Add(ToString(phraseBytes));
#endif
});
Console.WriteLine($"Done; time from start: {stopwatch.Elapsed}");
#if DEBUG
var anagramsArray = anagramsBag.ToArray();
var anagramsSet = new HashSet<string>(anagramsArray);
Array.Sort(anagramsArray);
Console.WriteLine("All anagrams:");
for (var i = 0; i < anagramsArray.Length; i++)
{
Console.WriteLine(anagramsArray[i]);
}
// Duplicate anagrams are expected, as e.g. "norway spoils tut tut" will be taken twice:
// as "norway1 spoils2 tut3 tut4" and "norway1 spoils2 tut4 tut3"
// (in addition to e.g. "norway1 tut3 spoils2 tut4")
Console.WriteLine($"Total anagrams count: {anagramsArray.Length}; unique anagrams: {anagramsSet.Count}; time from start: {stopwatch.Elapsed}");
#endif
}
// Code taken from http://stackoverflow.com/a/321404/831314
private static uint[] HexadecimalStringToUnsignedIntArray(string hex)
{
return Enumerable.Range(0, hex.Length)
.Where(x => x % 8 == 0)
.Select(x => ChangeEndianness(hex.Substring(x, 8)))
.Select(hexLe => Convert.ToUInt32(hexLe, 16))
.ToArray();
}
// Bouncy Castle is used instead of standard .NET methods for performance reasons
private static Vector<uint> ComputeHashVector(Phrase input)
{
return new Vector<uint>(MD5Digest.Compute(input));
}
private static string VectorToHexadecimalString(Vector<uint> hash)
{
var components = Enumerable.Range(0, 4)
.Select(i => hash[i].ToString("x8"))
.Select(ChangeEndianness);
return string.Concat(components);
}
private static string ChangeEndianness(string hex)
{
return hex.Substring(6, 2) + hex.Substring(4, 2) + hex.Substring(2, 2) + hex.Substring(0, 2);
}
private static string ToString(Phrase phrase)
{
return Encoding.ASCII.GetString(phrase.GetBytes());
}
private static IEnumerable<byte[]> ReadInput()
{
string line;
while ((line = Console.ReadLine()) != null)
{
yield return Encoding.ASCII.GetBytes(line);
}
}
private static string ToOrderedChars(string source)
{
return new string(source.Where(ch => ch != ' ').OrderBy(ch => ch).ToArray());
}
#if SINGLE_THREADED
private static void ForAll<T>(this IEnumerable<T> source, Action<T> action)
{
foreach (var entry in source)
{
action(entry);
}
}
#endif
}
}