day one

01/index.ts

@@ -0,0 +1,59 @@
+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
+    .map(
+      (v) => v.split(" ").filter((c) => c) // abusing js string nullity to remove empty members
+    )
+    .reduce(
+      (result, current) => {
+        // build two arrays, one of each column
+        result[0].push(parseInt(current[0], 10));
+        result[1].push(parseInt(current[1], 10));
+        return result;
+      },
+      [[], []] as Array<Array<number>>
+    )
+    .map((list) => [...list].sort()) // hacky return-sorted-values step
+    .reduce((result, current) => {
+      // rotate arrays into pairs
+      current.forEach((n, i) => {
+        result[i] === undefined ? (result[i] = [n]) : result[i].push(n);
+      });
+      return result;
+    }, [] as Array<Array<number>>)
+    .reduce((result, current) => {
+      // do the math
+      return result + Math.abs(current[0] - current[1]);
+    }, 0)
+);
+
+console.log(
+  "part two:",
+  Object.entries(
+    data
+      .split("\n")
+      .slice(0, -1) // remove empty trailing newline
+      .map(
+        (v) => v.split(" ").filter((c) => c) // abusing js string nullity to remove empty members
+      )
+      .reduce((result, current) => {
+        // build one object that contains the full set of frequencies
+        result[current[0]] = !result[current[0]]
+          ? [1, 0]
+          : [result[current[0]][0] + 1, result[current[0]][1]];
+        result[current[1]] = !result[current[1]]
+          ? [0, 1]
+          : [result[current[1]][0], result[current[1]][1] + 1];
+        return result;
+      }, [] as Array<Array<number>>)
+  ).reduce((result, current) => {
+    // and then just reduce down the object.
+    return result + parseInt(current[0], 10) * current[1][0] * current[1][1];
+  }, 0)
+);