day eleven both parts

11/code.js

@@ -0,0 +1,89 @@
+import { readFileSync } from 'node:fs';
+
+let sampleMode = true;
+
+const sampleArray1 = readFileSync('sample.txt').toString().split("\n");
+const sampleArray2 = readFileSync('sample2.txt').toString().split("\n");
+const inputArray = readFileSync('input.txt').toString().split("\n");
+
+const usedArray1 = sampleMode ? sampleArray1 : inputArray;
+const usedArray2 = sampleMode ? sampleArray2 : inputArray;
+
+// Part One
+
+console.time("part1");
+
+// Parse the graph
+const graph = new Map();
+
+for (const element of usedArray1) {
+  const [node, targets] = element.split(': ');
+  graph.set(node, targets.split(' '));
+}
+
+// Count paths from 'you' to 'out' using memoization
+const memo = new Map();
+
+function countPaths(node) {
+  if (node === 'out') return 1n;
+  if (memo.has(node)) return memo.get(node);
+  if (!graph.has(node)) return 0n;
+
+  let total = 0n;
+  for (const next of graph.get(node)) {
+    total += countPaths(next);
+  }
+
+  memo.set(node, total);
+  return total;
+}
+
+const part1 = countPaths('you');
+
+console.timeEnd("part1");
+console.log(part1.toString());
+
+
+// Part Two
+
+console.time("part2");
+
+// Re-parse graph for part 2 (may use different sample file)
+const graph2 = new Map();
+for (const element of usedArray2) {
+  const [node, targets] = element.split(': ');
+  graph2.set(node, targets.split(' '));
+}
+
+// Count paths between any two nodes using memoization
+const memo2 = new Map();
+
+function countPathsBetween(from, to) {
+  const key = `${from}->${to}`;
+  if (memo2.has(key)) return memo2.get(key);
+
+  if (from === to) return 1n;
+  if (!graph2.has(from)) return 0n;
+
+  let total = 0n;
+  for (const next of graph2.get(from)) {
+    total += countPathsBetween(next, to);
+  }
+
+  memo2.set(key, total);
+  return total;
+}
+
+// Paths from svr to out visiting both dac and fft:
+// Either: svr -> dac -> fft -> out
+// Or:     svr -> fft -> dac -> out
+
+const path1 = countPathsBetween('svr', 'dac') * countPathsBetween('dac', 'fft') * countPathsBetween('fft', 'out');
+const path2 = countPathsBetween('svr', 'fft') * countPathsBetween('fft', 'dac') * countPathsBetween('dac', 'out');
+
+const part2 = path1 + path2;
+
+console.timeEnd("part2");
+console.log(part2.toString());
+
+// functions