09/2024

Author: breadadams

2024/09/index.ts

@@ -0,0 +1,150 @@
+import { getPuzzle } from "../../utils";
+
+const puzzleInput = getPuzzle(__dirname).trim();
+const diskMap = puzzleInput.split("");
+
+// Part 1
+(() => {
+  console.time("part 1");
+  let representation = "";
+
+  for (let i = 0; i < diskMap.length; i++) {
+    const entry = Number(diskMap[i]);
+    const isFile = i % 2 === 0;
+
+    for (let j = 0; j < entry; j++) {
+      representation += `${isFile ? i / 2 : "."}_`;
+    }
+  }
+
+  let representationArr = representation
+    .split("_")
+    .filter((e) => e !== "")
+    .map((e) => (e === "." ? e : Number(e)));
+
+  let firstFreeSpaceBlockIndex = representationArr.indexOf(".");
+  let lastFileBlockIndex = representationArr.findLastIndex((e) => e !== ".");
+
+  while (lastFileBlockIndex > firstFreeSpaceBlockIndex) {
+    const lastEntry = representationArr.pop();
+
+    if (lastEntry !== ".") {
+      representationArr[firstFreeSpaceBlockIndex] = lastEntry;
+    }
+
+    firstFreeSpaceBlockIndex = representationArr.indexOf(".");
+    lastFileBlockIndex = representationArr.findLastIndex((e) => e !== ".");
+
+    if (firstFreeSpaceBlockIndex === -1) {
+      break;
+    }
+  }
+
+  let checksum = 0;
+
+  for (let i = 0; i < representationArr.length; i++) {
+    const block = representationArr[i];
+
+    if (block !== ".") {
+      checksum += block * i;
+    }
+  }
+
+  console.log("part 1 checksum ::", checksum);
+  console.timeEnd("part 1");
+})();
+
+// Part 2
+(() => {
+  console.time("part 2");
+  let representation = "";
+
+  for (let i = 0; i < diskMap.length; i++) {
+    const entry = Number(diskMap[i]);
+    const isFile = i % 2 === 0;
+
+    for (let j = 0; j < entry; j++) {
+      representation += `${isFile ? i / 2 : "."}_`;
+    }
+  }
+
+  let representationArr = representation
+    .split("_")
+    .filter((e) => e !== "")
+    .map((e) => (e === "." ? e : Number(e)));
+
+  const checkedNumbers = new Set<number>();
+
+  let i = representationArr.length;
+
+  while (true) {
+    i = i - 1;
+
+    if (i <= 0) {
+      break;
+    }
+
+    const num = representationArr[i];
+
+    if (num === "." || checkedNumbers.has(num)) {
+      continue;
+    }
+
+    checkedNumbers.add(num);
+
+    if (num === 0) {
+      break;
+    }
+
+    let fileSize = 1;
+    let j = i;
+
+    while (true) {
+      j = j - 1;
+      if (representationArr[j] === num) {
+        fileSize++;
+      } else {
+        break;
+      }
+    }
+
+    const availableSpace = representationArr.findIndex((entry, i, arr) => {
+      if (entry === ".") {
+        let match = true;
+
+        for (let k = 0; k < fileSize; k++) {
+          if (arr[i + k] !== ".") {
+            match = false;
+          }
+        }
+
+        return match;
+      }
+
+      return false;
+    });
+
+    if (availableSpace === -1 || availableSpace > j) {
+      continue;
+    }
+
+    for (let k = 0; k < fileSize; k++) {
+      representationArr[availableSpace + k] = num;
+
+      representationArr[j + 1 + k] = ".";
+    }
+  }
+
+  let checksum = 0;
+
+  for (let i = 0; i < representationArr.length; i++) {
+    const block = representationArr[i];
+
+    if (block !== ".") {
+      checksum += block * i;
+    }
+  }
+
+  console.log("part 2 checksum ::", checksum);
+  console.timeEnd("part 2");
+})();

README.md

@@ -6,6 +6,7 @@
 
 |                    Day                    | Part 1 | Part 2 |
 | :---------------------------------------: | :----: | :----: |
+| [09](https://adventofcode.com/2024/day/9) |   ✅   |   ✅   |
 | [08](https://adventofcode.com/2024/day/8) |   ✅   |   ✅   |
 | [07](https://adventofcode.com/2024/day/7) |   ✅   |   ✅   |
 | [06](https://adventofcode.com/2024/day/6) |   ✅   |   ✅   |

package-lock.json

@@ -14,6 +14,6 @@
     "inquirer": "^8.0.0",
     "nodemon": "^2.0.20",
     "ts-node": "^10.9.1",
-    "typescript": "^4.9.3"
+    "typescript": "^5.7.2"
   }
 }

package.json

@@ -2,6 +2,6 @@
   "compilerOptions": {
     "downlevelIteration": true,
     "esModuleInterop": true,
-    "lib": ["ES2021.String"]
+    "lib": ["ES2021.String", "ES2023.Array"]
   }
 }