AOC11.java

package aoc;

import java.awt.Point;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.Arrays;
import java.util.stream.Stream;

public class Day11 {

	enum Dirs {
		N(0,-1), NE(+1,-1),	E(+1,0), SE(+1,+1), S(0,+1), SW(-1,+1),	W(-1, 0), NW(-1,-1);
		
		int dx;
		int dy;
		private Dirs(int dx, int dy) {
			this.dx = dx;
			this.dy = dy;
		}
		
		public Point move(Point p)
		{
			return new Point(p.x+dx, p.y+dy);
		}
	};
	
	static int w;
	static int h;

	static boolean isInside(Point p)
	{
		return p.x>=0 && p.y>=0 && p.x<w && p.y<h;
	}
	static int countOccupied1(char[][] map, Point p)
	{
		return (int) Stream
				.of(Dirs.values())
				.map(d -> d.move(p))
				.filter(Day11::isInside)
				.filter(a ->  map[a.y][a.x]=='#')
				.count();
		
	}

	static char find(char[][] map, Point p, Dirs dir)
	{
		while(true) {
			p = dir.move(p);
			if(!isInside(p)) return '.';
			char c = map[p.y][p.x];
			if(c != '.') return c;
		}
		
	}
	static int countOccupied2(char[][] map, Point p)
	{
		return (int) Stream
				.of(Dirs.values())
				.map(d -> find(map, p, d))
				.filter(a ->  a=='#')
				.count();
		
	}

	public static boolean equal(final char[][] arr1, final char[][] arr2) {
		for (int i = 0; i < arr1.length; i++) {
			if (!Arrays.equals(arr1[i], arr2[i])) {
				return false;
			}
		}
		return true;
	}

	public static void main(String[] args) throws IOException {
		part1();
		part2();
	}
	private static void part1() throws IOException {
		char[][] src = Files.readAllLines(Paths.get("input11.txt")).stream().map(m -> m.toCharArray()).toArray(char[][]::new);
		char[][] dst = Files.readAllLines(Paths.get("input11.txt")).stream().map(m -> m.toCharArray()).toArray(char[][]::new);
		
		w = src[0].length;
		h = src.length;
		
		while(true)
		{
			step1(src, dst);
			if(equal(src,dst))
			{
				System.out.println(countAllOccupied(dst));
				
				return;
			}
			else
			{
				var s = src; src = dst; dst = s;
			}
		}
	}
	private static void part2() throws IOException {
		char[][] src = Files.readAllLines(Paths.get("input11.txt")).stream().map(m -> m.toCharArray()).toArray(char[][]::new);
		char[][] dst = Files.readAllLines(Paths.get("input11.txt")).stream().map(m -> m.toCharArray()).toArray(char[][]::new);
		
		w = src[0].length;
		h = src.length;
		
		while(true)
		{
			step2(src, dst);
			if(equal(src,dst))
			{
				System.out.println(countAllOccupied(dst));
				return;
			}
			else
			{
				var s = src; src = dst; dst = s;
			}
		}
	}
	private static int countAllOccupied(char[][] map) {
		int o = 0;
		for (int y = 0; y < h; y++) {
			for (int x = 0; x < w; x++) {
				if(map[y][x]=='#') o++;
			}
		}
		return o;
	}

	static void step1(char[][] src, char[][] dst) {
		for (int y = 0; y < h; y++) {
			for (int x = 0; x < w; x++) {
				if(src[y][x]!='.') {
					int o = countOccupied1(src, new Point( x, y ));
					switch (src[y][x]) {
					case 'L':
						dst[y][x] = (o == 0 ? '#' : 'L');
						break;
					case '#':
						dst[y][x] = (o >= 4 ? 'L' : '#');
						break;
					}
				}
			}
		}
	}
	static void step2(char[][] src, char[][] dst) {
		for (int y = 0; y < h; y++) {
			for (int x = 0; x < w; x++) {
				if(src[y][x]!='.') {
					int o = countOccupied2(src, new Point( x, y ));
					switch (src[y][x]) {
					case 'L':
						dst[y][x] = (o == 0 ? '#' : 'L');
						break;
					case '#':
						dst[y][x] = (o >= 5 ? 'L' : '#');
						break;
					}
				}
			}
		}
	}
	
	
}