day 4 done

03/index.ts

@@ -1,7 +1,11 @@
 import fs from "node:fs";
+import { Temporal } from "@js-temporal/polyfill";
+import { printTime } from "../util";
 
 const data = fs.readFileSync("./inputs/input", "utf8");
 
+let timer = Temporal.Now.instant();
+
 console.log(
   "part one:",
   data
@@ -45,9 +49,12 @@ console.log(
         }
       }
       return total;
-    }, 0)
+    }, 0),
+  printTime(Temporal.Now.instant().since(timer))
 );
 
+timer = Temporal.Now.instant();
+
 console.log(
   "part two:",
   data
@@ -124,5 +131,6 @@ console.log(
         return { ...total, on: state.on };
       },
       { sum: 0, on: true }
-    ).sum
+    ).sum,
+  printTime(Temporal.Now.instant().since(timer))
 );

04/index.ts

@@ -0,0 +1,103 @@
+import fs from "node:fs";
+import { printTime, now } from "../util";
+
+const test = false;
+
+const data = fs.readFileSync(
+  test ? "./inputs/testinput" : "./inputs/input",
+  "utf8"
+);
+
+let timer = now.instant();
+console.log(
+  "part one:",
+  data
+    .split("\n")
+    .slice(0, -1)
+    .reduce((coll, curr, index, array) => {
+      // 2D string matching is a pain. Let's turn it into a 1D problem!
+      // create the down rows
+      curr.split("").forEach((s, i) => {
+        coll[i] = coll[i] ? coll[i] + s : s;
+      });
+      // create the down-left-diagonals
+      curr.split("").forEach((s, i) => {
+        coll[i + array.length + index] = coll[i + array.length + index]
+          ? coll[i + array.length + index] + s
+          : s;
+      });
+      // create the down-right-diagonals
+      curr.split("").forEach((s, i) => {
+        coll[array.length * 4 + index - i - 2] = coll[
+          array.length * 4 + index - i - 2
+        ]
+          ? coll[array.length * 4 + index - i - 2] + s
+          : s;
+      });
+      // include the original crosses
+      return [...coll, curr];
+    }, Array.from({ length: test ? 10 + (10 * 4 - 2) : 140 + 140 * 4 - 2 }) as string[])
+    .reduce((total, curr) => {
+      // and now just do some regexes over the set of 1D strings
+      let matchesForward = curr.match(/XMAS/g);
+      let matchesBackward = curr.match(/SAMX/g);
+      if (matchesForward) {
+        total += matchesForward.length;
+      }
+      if (matchesBackward) {
+        total += matchesBackward.length;
+      }
+      return total;
+    }, 0),
+  printTime(now.instant().since(timer))
+);
+
+timer = now.instant();
+console.log(
+  "part two:",
+  data
+    .split("\n")
+    .slice(0, -1)
+    .reduce((coll, curr, index, array) => {
+      if (index === 0 || index === array.length - 1) {
+        // we can entirely skip the first and last rows, since there's no way to get a cross started
+        return coll;
+      }
+      // look for A's
+      curr.split("").forEach((s, i, a) => {
+        if (i === 0 || i === a.length - 1) {
+          // same as above, edges are useless
+          return;
+        }
+        if (s === "A") {
+          // 1 2
+          //  A
+          // 3 4
+          coll = [
+            ...coll,
+            array[index - 1][i - 1] +
+              array[index - 1][i + 1] +
+              array[index + 1][i - 1] +
+              array[index + 1][i + 1],
+          ];
+        }
+      });
+      return coll;
+    }, [] as string[])
+    .reduce((coll, curr) => {
+      // we could have just done this check above,
+      // but it's a little more clear, although slower,
+      // to iterate again.
+      switch (curr) {
+        case "MSMS":
+        case "SSMM":
+        case "SMSM":
+        case "MMSS":
+          coll += 1;
+        default:
+          break;
+      }
+      return coll;
+    }, 0),
+  printTime(now.instant().since(timer))
+);

index.tmpl.ts

@@ -1,13 +0,0 @@
-import fs from "node:fs";
-
-const data = fs.readFileSync("./inputs/input", "utf8");
-
-console.log(
-  "part one:",
-  data.split("\n").slice(0, -1) // remove empty trailing newline
-);
-
-console.log(
-  "part two:",
-  data.split("\n").slice(0, -1) // remove empty trailing newline
-);

index.ts.tmpl

@@ -0,0 +1,18 @@
+import fs from "node:fs";
+import { printTime, now } from "../util";
+
+const data = fs.readFileSync("./inputs/input", "utf8");
+
+let timer = now.instant();
+console.log(
+  "part one:",
+  data.split("\n").slice(0, -1),
+  printTime(now.instant().since(timer))
+);
+
+timer = now.instant();
+console.log(
+  "part two:",
+  data.split("\n").slice(0, -1),
+  printTime(now.instant().since(timer))
+);

package-lock.json

@@ -4,10 +4,26 @@
   "requires": true,
   "packages": {
     "": {
+      "dependencies": {
+        "@js-temporal/polyfill": "^0.4.4"
+      },
       "devDependencies": {
         "@types/node": "^22.10.1"
       }
     },
+    "node_modules/@js-temporal/polyfill": {
+      "version": "0.4.4",
+      "resolved": "https://registry.npmjs.org/@js-temporal/polyfill/-/polyfill-0.4.4.tgz",
+      "integrity": "sha512-2X6bvghJ/JAoZO52lbgyAPFj8uCflhTo2g7nkFzEQdXd/D8rEeD4HtmTEpmtGCva260fcd66YNXBOYdnmHqSOg==",
+      "license": "ISC",
+      "dependencies": {
+        "jsbi": "^4.3.0",
+        "tslib": "^2.4.1"
+      },
+      "engines": {
+        "node": ">=12"
+      }
+    },
     "node_modules/@types/node": {
       "version": "22.10.1",
       "resolved": "https://registry.npmjs.org/@types/node/-/node-22.10.1.tgz",
@@ -18,6 +34,18 @@
         "undici-types": "~6.20.0"
       }
     },
+    "node_modules/jsbi": {
+      "version": "4.3.0",
+      "resolved": "https://registry.npmjs.org/jsbi/-/jsbi-4.3.0.tgz",
+      "integrity": "sha512-SnZNcinB4RIcnEyZqFPdGPVgrg2AcnykiBy0sHVJQKHYeaLUvi3Exj+iaPpLnFVkDPZIV4U0yvgC9/R4uEAZ9g==",
+      "license": "Apache-2.0"
+    },
+    "node_modules/tslib": {
+      "version": "2.8.1",
+      "resolved": "https://registry.npmjs.org/tslib/-/tslib-2.8.1.tgz",
+      "integrity": "sha512-oJFu94HQb+KVduSUQL7wnpmqnfmLsOA/nAh6b6EH0wCEoK0/mPeXU6c3wKDV83MkOuHPRHtSXKKU99IBazS/2w==",
+      "license": "0BSD"
+    },
     "node_modules/undici-types": {
       "version": "6.20.0",
       "resolved": "https://registry.npmjs.org/undici-types/-/undici-types-6.20.0.tgz",

package.json

@@ -1,5 +1,8 @@
 {
   "devDependencies": {
     "@types/node": "^22.10.1"
+  },
+  "dependencies": {
+    "@js-temporal/polyfill": "^0.4.4"
   }
 }

today.sh

@@ -16,6 +16,6 @@ if [ ! -f "${padded}/inputs/input" ]; then
         -H "Cookie: session=`cat .cookie`" https://adventofcode.com/${__year}/day/${__day##0}/input > "${padded}/inputs/input"
 fi
 if [ ! -f "${padded}/index.ts" ]; then
-    cp index.tmpl.ts ${padded}/index.ts
+    cp index.ts.tmpl ${padded}/index.ts
 fi
 open "https://adventofcode.com/${__year}/day/${__day##0}"

util.ts

@@ -0,0 +1,19 @@
+import { Temporal } from "@js-temporal/polyfill";
+
+export const now = Temporal.Now;
+
+export const printTime = (duration: Temporal.Duration): string => {
+  const units = [
+    { unit: "m", value: duration.minutes },
+    { unit: "s", value: duration.seconds },
+    { unit: "ms", value: duration.milliseconds },
+    { unit: "µs", value: duration.microseconds },
+    { unit: "ns", value: duration.nanoseconds },
+  ];
+
+  const parts = units
+    .filter((u) => u.value !== 0)
+    .map((u) => `${u.value} ${u.unit}`);
+
+  return parts.join(", ");
+};