Day14.java

package com.sbaars.adventofcode.year22.days;

import com.sbaars.adventofcode.common.grid.InfiniteGrid;
import com.sbaars.adventofcode.common.location.Loc;
import com.sbaars.adventofcode.common.location.MutableLoc;
import com.sbaars.adventofcode.common.location.Range;
import com.sbaars.adventofcode.util.AoCUtils;
import com.sbaars.adventofcode.year22.Day2022;

import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.Stream;

import static com.sbaars.adventofcode.common.Direction.*;
import static com.sbaars.adventofcode.common.grid.InfiniteGrid.toInfiniteGrid;
import static com.sbaars.adventofcode.util.DataMapper.readString;

public class Day14 extends Day2022 {
  public Day14() {
    super(14);
  }

  public static void main(String[] args) {
    new Day14().printParts();
  }

  @Override
  public Object part1() {
    return amountOfSand(true);
  }

  @Override
  public Object part2() {
    return amountOfSand(false);
  }

  public record Path(List<Loc> locs) {
  }

  public int amountOfSand(boolean part1) {
    List<Path> paths = dayStream()
        .map(s -> readString(s, "%l(%n,%n)", " -> ", Path.class, Loc.class))
        .collect(Collectors.toCollection(ArrayList::new));
    if (!part1) {
      long maxY = paths.stream().flatMapToLong(e -> e.locs.stream().mapToLong(f -> f.y)).max().getAsLong() + 2;
      paths.add(new Path(List.of(new Loc(0, maxY), new Loc(999, maxY))));
    }
    InfiniteGrid g = constructWalls(paths);
    return simulateSand(part1, g);
  }

  private static InfiniteGrid constructWalls(List<Path> paths) {
    return paths.stream()
        .map(Path::locs)
        .flatMap(AoCUtils::connectedPairs)
        .map(Range::new)
        .flatMap(Range::stream)
        .collect(toInfiniteGrid('#'));
  }

  private static int simulateSand(boolean part1, InfiniteGrid g) {
    Loc sandOrigin = new Loc(500, 0);
    MutableLoc fallingSand = new MutableLoc(sandOrigin);
    while (part1 ? fallingSand.get().y < 950 : g.get(sandOrigin).isEmpty()) {
      Loc moveTo = Stream.of(SOUTH, SOUTHWEST, SOUTHEAST, CENTER)
          .map(d -> d.move(fallingSand.get()))
          .filter(p -> g.get(p).isEmpty())
          .findFirst()
          .get();
      if (moveTo.equals(fallingSand.get())) {
        g.set(fallingSand.get(), 'o');
        fallingSand.set(sandOrigin);
      } else {
        fallingSand.set(moveTo);
      }
    }
    return g.countChar('o');
  }
}