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AoC2025_09.java
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106 lines (91 loc) · 3.58 KB
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import com.github.pareronia.aoc.Grid.Cell;
import com.github.pareronia.aoc.StringOps;
import com.github.pareronia.aoc.StringOps.StringSplit;
import com.github.pareronia.aoc.itertools.IterTools;
import com.github.pareronia.aoc.Utils;
import com.github.pareronia.aoc.solution.Sample;
import com.github.pareronia.aoc.solution.Samples;
import com.github.pareronia.aoc.solution.SolutionBase;
import java.util.List;
import java.util.stream.Stream;
@SuppressWarnings({"PMD.ClassNamingConventions", "PMD.NoPackage"})
public final class AoC2025_09 extends SolutionBase<List<Cell>, Long, Long> {
private AoC2025_09(final boolean debug) {
super(debug);
}
public static AoC2025_09 create() {
return new AoC2025_09(false);
}
public static AoC2025_09 createDebug() {
return new AoC2025_09(true);
}
@Override
protected List<Cell> parseInput(final List<String> inputs) {
return inputs.stream()
.map(
line -> {
final StringSplit split = StringOps.splitOnce(line, ",");
return Cell.at(
Integer.parseInt(split.right()),
Integer.parseInt(split.left()));
})
.toList();
}
@Override
public Long solvePart1(final List<Cell> reds) {
return rectangles(reds).mapToLong(Rectangle::getArea).max().getAsLong();
}
@Override
public Long solvePart2(final List<Cell> reds) {
final List<Rectangle> borderSegments =
IterTools.pairwise(Stream.concat(reds.stream(), Stream.of(reds.getFirst())))
.stream()
.map(pair -> Rectangle.from(pair.first(), pair.second()))
.toList();
return rectangles(reds)
.filter(rect -> borderSegments.stream().noneMatch(rect::intersects))
.mapToLong(Rectangle::getArea)
.max()
.getAsLong();
}
@Samples({
@Sample(method = "part1", input = TEST, expected = "50"),
@Sample(method = "part2", input = TEST, expected = "24"),
})
public static void main(final String[] args) throws Exception {
create().run();
}
private static final String TEST =
"""
7,1
11,1
11,7
9,7
9,5
2,5
2,3
7,3
""";
record Rectangle(int minRow, int minCol, int maxRow, int maxCol) {
public static Rectangle from(final Cell first, final Cell second) {
final int minRow = Math.min(first.getRow(), second.getRow());
final int maxRow = Math.max(first.getRow(), second.getRow());
final int minCol = Math.min(first.getCol(), second.getCol());
final int maxCol = Math.max(first.getCol(), second.getCol());
return new Rectangle(minRow, minCol, maxRow, maxCol);
}
public boolean intersects(final Rectangle other) {
return !(this.maxCol <= other.minCol
|| this.minCol >= other.maxCol
|| this.maxRow <= other.minRow
|| this.minRow >= other.maxRow);
}
public long getArea() {
return (long) (maxRow - minRow + 1) * (maxCol - minCol + 1);
}
}
private Stream<Rectangle> rectangles(final List<Cell> reds) {
return Utils.stream(IterTools.combinations(reds.size(), 2))
.map(combo -> Rectangle.from(reds.get(combo[0]), reds.get(combo[1])));
}
}