projEuler14.ts

inputs/passing/projEuler14.ts

@@ -0,0 +1,40 @@
+declare const Debug: {
+  log: (...args: unknown[]) => undefined;
+};
+
+export default function main() {
+  let longest = {
+    n: 1,
+    len: 1,
+  };
+
+  for (let n = 2; n < 1000000; n++) {
+    if (n % 50000 === 0) {
+      Debug.log(n);
+    }
+
+    const len = collatzLen(n);
+
+    if (len > longest.len) {
+      longest = { n, len };
+    }
+  }
+
+  return longest;
+}
+
+function collatzLen(n: number) {
+  let i = 1;
+
+  while (n !== 1) {
+    if (n % 2 === 0) {
+      n /= 2;
+      i++;
+    } else {
+      n = (3 * n + 1) / 2;
+      i += 2;
+    }
+  }
+
+  return i;
+}