package y2016.d14;

import org.apache.commons.codec.binary.Hex;

import java.security.MessageDigest;

import java.security.NoSuchAlgorithmException;

import java.util.HashMap;

import java.util.HashSet;

import java.util.regex.Matcher;

import java.util.regex.Pattern;

public class Part2 {

private static MessageDigest md5;

private static Pattern pattern1 = Pattern.compile("([a-f0-9])(\\1{2})");

// private static String salt = "abc";

private static String salt = "cuanljph";

private static HashMap<Integer, String> hashMap = new HashMap<Integer, String>();

public static void main(String[] args) throws NoSuchAlgorithmException {

md5 = MessageDigest.getInstance("MD5");

HashSet<String> keys = new HashSet<String>();

int count = 0;

while (keys.size() < 64) {

String hash = hashOrDie(count);

String result3 = getCharOfSequenceOfThree(hash);

if (null != result3) {

String hash2;

for (int i = count + 1; i < count + 1000; i++) {

hash2 = hashOrDie(i);

if (hasSequenceOfFive(hash2, result3)) {

System.out.print("three (" + result3 + "):" + hash + " @ " + count);

System.out.print(" five (" + result3 + "):" + hash2 + " @ " + i + " | ");

keys.add(hash);

System.out.println(keys.size());

break;

}

}

}

++count;

}

System.out.println(count-1);

}

private static String hashOrDie(int count) {

if (hashMap.containsKey(count)) {

return hashMap.get(count);

}

String hash = getMd5Hex(salt + count);

for (int i = 0; i < 2016; i++ ) {

hash = getMd5Hex(hash);

}

hashMap.put(count, hash);

return hash;

}

private static String getCharOfSequenceOfThree(String hash) {

Matcher matcher = pattern1.matcher(hash);

if (matcher.find()) {

return matcher.group(1);

}

return null;

}

private static boolean hasSequenceOfFive(String hash, String character) {

return hash.matches(".*" + character + "{5}.*");

}

private static String getMd5Hex(String input) {

byte[] hashInBytes = md5.digest(input.getBytes());

return Hex.encodeHexString(hashInBytes);

}

}