adventofcode/src/main/java/AoC2015_04.java at main · pareronia/adventofcode · GitHub

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import static com.github.pareronia.aoc.IntegerSequence.Range.range;

import java.util.List;

import java.util.stream.IntStream;

import com.github.pareronia.aoc.codec.MD5;

import com.github.pareronia.aoc.solution.Sample;

import com.github.pareronia.aoc.solution.Samples;

import com.github.pareronia.aoc.solution.SolutionBase;

public final class AoC2015_04

extends SolutionBase<AoC2015_04.AdventCoinsMiner, Integer, Integer> {

private AoC2015_04(final boolean debug) {

super(debug);

}

public static AoC2015_04 create() {

return new AoC2015_04(false);

}

public static AoC2015_04 createDebug() {

return new AoC2015_04(true);

}

@Override

protected AdventCoinsMiner parseInput(final List<String> inputs) {

assert inputs.size() == 1;

return new AdventCoinsMiner(inputs.get(0));

}

@Override

public Integer solvePart1(final AdventCoinsMiner miner) {

return miner.findMd5StartingWithZeroes(5);

}

@Override

public Integer solvePart2(final AdventCoinsMiner miner) {

return miner.findMd5StartingWithZeroes(6);

}

@Override

@Samples({

@Sample(method = "part1", input = TEST1, expected = "609043"),

@Sample(method = "part1", input = TEST2, expected = "1048970"),

})

public void samples() {

super.samples();

}

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

AoC2015_04.create().run();

}

private static final String TEST1 = "abcdef";

private static final String TEST2 = "pqrstuv";

record AdventCoinsMiner(String secretKey) {

private boolean checkZeroes(final byte[] digest, final int zeroes) {

int cnt = 0;

for (final int j : range(zeroes / 2 + zeroes % 2)) {

final byte c = digest[j];

if ((c & 0xF0) != 0) {

break;

}

cnt++;

if ((c & 0x0F) != 0) {

break;

}

cnt++;

}

return cnt == zeroes;

}

public int findMd5StartingWithZeroes(final int zeroes) {

return IntStream.iterate(1, i -> i + 1)

.dropWhile(i -> {

final String data = this.secretKey + String.valueOf(i);

return !checkZeroes(MD5.md5(data), zeroes);

})

.findFirst().getAsInt();

}

adventofcode/src/main/java/AoC2015_04.java at main · pareronia/adventofcode · GitHub

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