adventofcode/src/main/java/AoC2017_03.java at main · pareronia/adventofcode · GitHub

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import com.github.pareronia.aoc.AssertUtils;

import com.github.pareronia.aoc.geometry.Direction;

import com.github.pareronia.aoc.geometry.Position;

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

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

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

import java.util.HashMap;

import java.util.Iterator;

import java.util.List;

import java.util.Map;

import java.util.function.Function;

import java.util.function.Supplier;

public final class AoC2017_03 extends SolutionBase<Integer, Integer, Integer> {

private AoC2017_03(final boolean debug) {

super(debug);

}

public static AoC2017_03 create() {

return new AoC2017_03(false);

}

public static AoC2017_03 createDebug() {

return new AoC2017_03(true);

}

@Override

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

return Integer.valueOf(inputs.getFirst());

}

record DirectionAndPeriod(Direction direction, int period) {

public static DirectionAndPeriod of(final Direction direction, final int period) {

return new DirectionAndPeriod(direction, period);

}

private static class CoordinateSupplier implements Supplier<Position> {

private final Function<Integer, DirectionAndPeriod> directionsAndPeriods =

new Function<>() {

private final List<Direction> directions =

List.of(

Direction.RIGHT, Direction.UP,

Direction.LEFT, Direction.DOWN);

private final int[] periods = {1, 1, 2, 2};

@Override

public DirectionAndPeriod apply(final Integer t) {

final int idx = t % 4;

final int period = periods[idx];

periods[idx] = period + 2;

final Direction direction = directions.get(idx);

return DirectionAndPeriod.of(direction, period);

}

};

private int x;

private int y;

private int k;

private DirectionAndPeriod directionAndPeriod = directionsAndPeriods.apply(k);

private int j;

@Override

public Position get() {

if (j == directionAndPeriod.period) {

k++;

directionAndPeriod = directionsAndPeriods.apply(k);

j = 0;

}

x += directionAndPeriod.direction.getX();

y += directionAndPeriod.direction.getY();

j++;

return Position.of(x, y);

}

@Override

public Integer solvePart1(final Integer input) {

if (input == 1) {

return 0;

}

final CoordinateSupplier supplier = new CoordinateSupplier();

int i = 1;

while (i < input) {

i++;

final Position position = supplier.get();

if (i == input) {

return position.manhattanDistance();

}

throw AssertUtils.unreachable();

}

@Override

public Integer solvePart2(final Integer input) {

if (input == 1) {

return 1;

}

final Map<Position, Integer> squares = new HashMap<>();

squares.put(Position.of(0, 0), 1);

final CoordinateSupplier supplier = new CoordinateSupplier();

while (true) {

final Position position = supplier.get();

int value = 0;

final Iterator<Position> it = position.allNeighbours().iterator();

while (it.hasNext()) {

value += squares.getOrDefault(it.next(), 0);

}

squares.put(position, value);

if (value > input) {

return value;

}

@Samples({

@Sample(method = "part1", input = "1", expected = "0"),

@Sample(method = "part1", input = "12", expected = "3"),

@Sample(method = "part1", input = "23", expected = "2"),

@Sample(method = "part1", input = "1024", expected = "31"),

@Sample(method = "part2", input = "1", expected = "1"),

@Sample(method = "part2", input = "2", expected = "4"),

@Sample(method = "part2", input = "3", expected = "4"),

@Sample(method = "part2", input = "4", expected = "5"),

@Sample(method = "part2", input = "5", expected = "10"),

})

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

create().run();

}

adventofcode/src/main/java/AoC2017_03.java at main · pareronia/adventofcode · GitHub

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