feat: Event 2018 day 18

Author: vuryss

core/src/main/java/com/vuryss/aoc/solutions/event2018/Day18.java

@@ -0,0 +1,121 @@
+package com.vuryss.aoc.solutions.event2018;
+
+import com.vuryss.aoc.solutions.SolutionInterface;
+import com.vuryss.aoc.util.Point;
+
+import java.lang.Override;
+import java.lang.String;
+import java.lang.SuppressWarnings;
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.Map;
+
+@SuppressWarnings("unused")
+public class Day18 implements SolutionInterface {
+ @Override
+ public Map<String, String> part1Tests() {
+ return Map.of(
+ """
+ .#.#...|#.
+ .....#|##|
+ .|..|...#.
+ ..|#.....#
+ #.#|||#|#|
+ ...#.||...
+ .|....|...
+ ||...#|.#|
+ |.||||..|.
+ ...#.|..|.
+ """,
+ "1147"
+ );
+ }
+
+ @Override
+ public Map<String, String> part2Tests() {
+ return Map.of();
+ }
+
+ @Override
+ public String part1Solution(String input, boolean isTest) {
+ return calculateResourceValue(input, 10);
+ }
+
+ @Override
+ public String part2Solution(String input, boolean isTest) {
+ return calculateResourceValue(input, 1000000000);
+ }
+
+ private int gridHash(char[][] grid) {
+ return Arrays.deepHashCode(grid);
+ }
+
+ private String calculateResourceValue(String input, int minutes) {
+ char[][] grid = Arrays.stream(input.trim().split("\n")).map(String::toCharArray).toArray(char[][]::new);
+ int size = grid.length;
+ Point point;
+ var seen = new HashMap<Integer, Integer>();
+ seen.put(gridHash(grid), 0);
+ var foundCycle = false;
+
+ for (var i = 0; i < minutes; i++) {
+ char[][] newGrid = new char[size][size];
+
+ for (var y = 0; y < size; y++) {
+ for (var x = 0; x < size; x++) {
+ int trees = 0, lumberyards = 0;
+
+ for (var p: new Point(x, y).surroundingPoints()) {
+ if (p.x < 0 || p.x >= size || p.y < 0 || p.y >= size) {
+ continue;
+ }
+
+ if (grid[p.y][p.x] == '|') {
+ trees++;
+ } else if (grid[p.y][p.x] == '#') {
+ lumberyards++;
+ }
+ }
+
+ if (grid[y][x] == '.') {
+ newGrid[y][x] = trees >= 3 ? '|' : '.';
+ } else if (grid[y][x] == '|') {
+ newGrid[y][x] = lumberyards >= 3 ? '#' : '|';
+ } else {
+ newGrid[y][x] = lumberyards >= 1 && trees >= 1 ? '#' : '.';
+ }
+ }
+ }
+
+ grid = newGrid;
+
+ if (foundCycle) {
+ continue;
+ }
+
+ if (seen.containsKey(gridHash(grid))) {
+ int cycleSize = i - seen.get(gridHash(grid));
+ int minutesLeft = minutes - i;
+ int leftFromLastCycle = minutesLeft % cycleSize;
+ i = minutes - leftFromLastCycle;
+ foundCycle = true;
+ } else {
+ seen.put(gridHash(grid), i);
+ }
+ }
+
+ int trees = 0, lumberyards = 0;
+
+ for (var row: grid) {
+ for (var c: row) {
+ if (c == '|') {
+ trees++;
+ } else if (c == '#') {
+ lumberyards++;
+ }
+ }
+ }
+
+ return String.valueOf(trees * lumberyards);
+ }
+}