1 files changed, 42 insertions, 0 deletions
diff --git a/day-8/script.ts b/day-8/script.ts
new file mode 100644
index 0000000..71849c7
--- /dev/null
+++ b/day-8/script.ts
@@ -0,0 +1,42 @@
+import fs from "fs";
+
+const [directions, _, ...lines] = fs
+  .readFileSync("./input.txt")
+  .toString()
+  .split("\n")
+  .slice(0, -1);
+
+const nodes = lines
+  .map((line) => {
+    const match = line.match(/(...) = \((...), (...)\)/);
+    if (!match) throw new Error("Could not match");
+    return {
+      node: match[1],
+      left: match[2],
+      right: match[3],
+    };
+  })
+  .map((node, index, nodes) => ({
+    node: index,
+    left: nodes.findIndex((n) => n.node === node.left),
+    right: nodes.findIndex((n) => n.node === node.right),
+  }));
+
+const targetNumber = lines.findIndex((line) => line.startsWith("ZZZ"));
+let currentNumber = lines.findIndex((line) => line.startsWith("AAA"));
+
+let steps = 0;
+while (currentNumber !== targetNumber) {
+  const direction = (
+    {
+      L: "left",
+      R: "right",
+    } as const
+  )[directions[steps % directions.length]];
+  if (!direction) throw new Error("Invalid direction");
+
+  currentNumber = nodes[currentNumber][direction];
+  steps++;
+}
+
+console.log({ steps });