Day11a: Solved

lib/day11.dart

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+// --- Day 11: Plutonian Pebbles ---
+// https://adventofcode.com/2024/day/11
+
+import 'dart:collection';
+
+final class Stone extends LinkedListEntry<Stone> {
+  int value;
+
+  Stone(this.value);
+}
+
+int solveA(String input, {int blink = 25}) => solve(input, blink: blink);
+int solveB(String input) => solve(input, blink: 75);
+
+int solve(String input, {int blink = 25}) {
+  final stones = LinkedList<Stone>();
+
+  for (final stoneValue in input.split(' ').map(int.parse)) {
+    stones.add(Stone(stoneValue));
+  }
+
+  for (var i = 0; i < blink; i++) {
+    Stone? stone = stones.first;
+
+    while (stone != null) {
+      if (stone.value == 0) {
+        stone.value = 1;
+      } else if (stone.value.toString() case final numberString
+          when numberString.length % 2 == 0) {
+        stone.insertBefore(Stone(
+            int.parse(numberString.substring(0, numberString.length ~/ 2))));
+        stone.value =
+            int.parse(numberString.substring(numberString.length ~/ 2));
+      } else {
+        stone.value *= 2024;
+      }
+
+      stone = stone.next;
+    }
+  }
+
+  return stones.length;
+}

test/day11_test.dart

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+// --- Day 11: Plutonian Pebbles ---
+// https://adventofcode.com/2024/day/11
+
+import 'dart:io';
+import 'package:advent_of_code_2024/day11.dart';
+import 'package:test/test.dart';
+
+final input = File('test/data/day11.txt').readAsLinesSync().first;
+
+void main() {
+  group('Part One', () {
+    test('Example 1', () {
+      expect(solveA('0 1 10 99 999', blink: 1), equals(7));
+    });
+    test('Example 2', () {
+      expect(solveA('125 17', blink: 1), equals(3));
+    });
+    test('Example 3', () {
+      expect(solveA('125 17', blink: 6), equals(22));
+    });
+    test('Example 4', () {
+      expect(solveA('125 17'), equals(55312));
+    });
+    test('Solution', () {
+      expect(solveA(input), equals(193607));
+    });
+  });
+  group('Part Two', () {
+    test('Solution', () {
+      expect(solveB(input), equals(-1));
+    });
+  }, skip: true);
+}