Day 3

03/part1.js

@@ -0,0 +1,20 @@
+const { readFileSync } = require("fs");
+// Parse Input
+const inputFile = "input.txt";
+const input = readFileSync(inputFile).toString();
+
+// Apply Regex
+const regex = /mul\((\d+),\s*(\d+)\)/g;
+let match,
+  groups = [];
+while ((match = regex.exec(input)) !== null) {
+  groups.push({ x: parseInt(match[1]), y: parseInt(match[2]) });
+}
+
+// Compute Result
+let result = 0;
+groups.forEach((g) => {
+  result += g.x * g.y;
+});
+
+console.log(result);

03/part2.js

@@ -0,0 +1,37 @@
+const { readFileSync } = require("fs");
+// Parse Input
+const inputFile = "input.txt";
+const input = readFileSync(inputFile).toString();
+
+// Apply Regex
+const regex = /mul\((\d+),\s*(\d+)\)|do\(\)|don't\(\)/g;
+let match,
+  op = [];
+while ((match = regex.exec(input)) !== null) {
+  if (match[1] && match[2]) {
+    op.push({ type: "mul", x: parseInt(match[1]), y: parseInt(match[2]) });
+  } else if (match[0] === "do()") {
+    op.push({ type: "do" });
+  } else if (match[0] === "don't()") {
+    op.push({ type: "don't" });
+  }
+}
+
+// Compute Result
+let result = 0;
+let enabled = true;
+op.forEach((g) => {
+  switch (g.type) {
+    case "mul":
+      if (enabled) result += g.x * g.y;
+      break;
+    case "do":
+      enabled = true;
+      break;
+    case "don't":
+      enabled = false;
+      break;
+  }
+});
+
+console.log(result);