adventofcode/src/main/java/AoC2023_09.java at main · pareronia/adventofcode · GitHub

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import static com.github.pareronia.aoc.itertools.IterTools.zip;

import com.github.pareronia.aoc.ListUtils;

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

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

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

import java.util.ArrayDeque;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.Deque;

import java.util.List;

@SuppressWarnings({"PMD.ClassNamingConventions", "PMD.NoPackage"})

public final class AoC2023_09 extends SolutionBase<List<List<Integer>>, Integer, Integer> {

private AoC2023_09(final boolean debug) {

super(debug);

}

public static AoC2023_09 create() {

return new AoC2023_09(false);

}

public static AoC2023_09 createDebug() {

return new AoC2023_09(true);

}

@Override

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

return inputs.stream()

.map(line -> Arrays.stream(line.split(" ")).map(Integer::valueOf).toList())

.toList();

}

private int solve(final List<Integer> lineIn) {

List<Integer> line = new ArrayList<>(lineIn);

final Deque<Integer> tails = new ArrayDeque<>(List.of(line.getLast()));

while (!line.stream().allMatch(tails.peekLast()::equals)) {

line =

zip(line, line.subList(1, line.size())).stream()

.map(z -> z.second() - z.first())

.toList();

tails.addLast(line.getLast());

}

return tails.stream().mapToInt(Integer::valueOf).sum();

}

@Override

public Integer solvePart1(final List<List<Integer>> input) {

return input.stream().mapToInt(this::solve).sum();

}

@Override

public Integer solvePart2(final List<List<Integer>> input) {

return input.stream().map(ListUtils::reversed).mapToInt(this::solve).sum();

}

@Samples({

@Sample(method = "part1", input = TEST, expected = "114"),

@Sample(method = "part2", input = TEST, expected = "2"),

})

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

create().run();

}

private static final String TEST =

"""

0 3 6 9 12 15

1 3 6 10 15 21

10 13 16 21 30 45

""";

}

adventofcode/src/main/java/AoC2023_09.java at main · pareronia/adventofcode · GitHub

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