ugh day 2 part 2 sucked

02/index.ts

@@ -0,0 +1,66 @@
+import fs from "node:fs";
+
+const data = fs.readFileSync("./inputs/input", "utf8");
+
+type runner = { ok: boolean; prev: number; inc: boolean; dec: boolean };
+
+const testFunc = (running: runner, current: number, i: number) => {
+  if (i === 0) {
+    return { ok: true, prev: current, inc: false, dec: false };
+  }
+  if (!running.ok) {
+    // quick exit
+    return running;
+  }
+  const diff = Math.abs(running.prev - current);
+  return {
+    ok: diff > 0 && diff < 4,
+    prev: current,
+    inc: running.inc || running.prev - current > 0,
+    dec: running.dec || running.prev - current < 0,
+  };
+};
+
+const permute = (report: number[]): number[][] => {
+  const result: Array<Array<number>> = Array.from(
+    { length: report.length },
+    () => []
+  );
+  return result.map((_, i) => {
+    return [...report.slice(0, i), ...report.slice(i + 1)];
+  });
+};
+
+console.log(
+  "part one:",
+  data
+    .split("\n")
+    .slice(0, -1) // remove empty trailing newline
+    .map((v) => v.split(" ").map((c) => parseInt(c, 10)))
+    .reduce((total, current) => {
+      const tmp = current.reduce(testFunc, {} as runner);
+      return (tmp.inc && tmp.dec) || !tmp.ok ? total : total + 1;
+    }, 0)
+);
+
+console.log(
+  "part two:",
+  data
+    .split("\n")
+    .slice(0, -1) // remove empty trailing newline
+    .map((v) => v.split(" ").map((c) => parseInt(c, 10)))
+    .reduce((total, current) => {
+      const tmp = current.reduce(testFunc, {} as runner);
+      // ok, that was fine.
+      if (tmp.ok && !(tmp.inc && tmp.dec)) {
+        return total + 1;
+      }
+      // otherwise, brute force!
+      const tmp2 = permute(current)
+        .map((v) => v.reduce(testFunc, {} as runner))
+        .reduce((coll, curr) => {
+          return coll || (curr.ok && !(curr.inc && curr.dec));
+        }, false);
+      return tmp2 ? total + 1 : total;
+    }, 0)
+);