clean up the code a little more

04/index.ts

@@ -14,31 +14,30 @@ console.log(
   data
     .split("\n")
     .slice(0, -1)
-    .reduce((coll, curr, index, array) => {
+    .reduce(
+      (coll, curr, index, array) => {
         // 2D string matching is a pain. Let's turn it into a 1D problem!
         // create the columns
         curr.split("").forEach((s, i) => {
-        coll[i] = coll[i] ? coll[i] + s : s;
+          coll[i] += 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;
+          coll[i + array.length + index] += 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;
+          coll[array.length * 4 + index - i - 2] += s;
         });
         // include the original row
         return [...coll, curr];
-    }, Array.from({ length: test ? 10 + (10 * 4 - 2) : 140 + 140 * 4 - 2 }) as string[])
+      },
+      // pre-populate the array so everything's aligned
+      Array.from({ length: test ? 10 * 5 - 2 : 140 * 5 - 2 }, () => "")
+    )
     .reduce((total, curr) => {
       // and now just do some regexes over the set of 1D strings
+      // can't do /XMAS|SMAX/ because overlaps like XMASAMX are allowed!
       let matchesForward = curr.match(/XMAS/g);
       let matchesBackward = curr.match(/SAMX/g);
       if (matchesForward) {
@@ -64,25 +63,28 @@ console.log(
         return coll;
       }
       // look for A's
-      curr.split("").forEach((s, i, a) => {
+      return [
+        ...coll,
+        ...curr.split("").reduce((c, s, i, a) => {
           if (i === 0 || i === a.length - 1) {
             // same as above, edges are useless
-          return;
+            return c;
           }
-        if (s === "A") {
           // 1 2
           //  A
           // 3 4
-          coll = [
-            ...coll,
+          if (s === "A") {
+            return [
+              ...c,
               array[index - 1][i - 1] +
                 array[index - 1][i + 1] +
                 array[index + 1][i - 1] +
                 array[index + 1][i + 1],
             ];
           }
-      });
-      return coll;
+          return c;
+        }, [] as string[]),
+      ];
     }, [] as string[])
     .reduce((coll, curr) => {
       // we could have just done this check above,

index.ts.tmpl

@@ -1,7 +1,12 @@
 import fs from "node:fs";
 import { printTime, now } from "../util";
 
-const data = fs.readFileSync("./inputs/input", "utf8");
+const test = false;
+
+const data = fs.readFileSync(
+  test ? "./inputs/testinput" : "./inputs/input",
+  "utf8"
+);
 
 let timer = now.instant();
 console.log(