Solve 9

src/9/index.ts

@@ -0,0 +1,75 @@
+import fs from "fs"
+const content = fs.readFileSync('input.txt', 'utf-8');
+const disk:string[] = [];
+let fileId = 0;
+for (let i = 0; i < content.length; i++) {
+    const amount = Number(content[i]);
+    if (i % 2 === 0) {
+        for (let j = 0; j < amount; j++) {
+            disk.push(fileId.toString(10))
+        }
+        fileId++;
+    } else {
+        for (let j = 0; j < amount; j++) {
+            disk.push(".")
+        }
+    }
+}
+const orderedDisk = structuredClone(disk);
+let backIndex = orderedDisk.length-1
+for (let i = 0; i < backIndex; i++) {
+    if (orderedDisk[i] === ".") {
+        orderedDisk[i] = orderedDisk[backIndex]
+        orderedDisk[backIndex] = "."
+        while (orderedDisk[backIndex] === ".") {
+            backIndex--
+        }
+    }
+}
+let checksum = 0;
+for (let i = 0; i < orderedDisk.length; i++) {
+    if (orderedDisk[i] !== ".") {
+        checksum += i * Number(orderedDisk[i])
+    }
+}
+console.log(checksum)
+const fragmented = structuredClone(disk);
+backIndex = fragmented.length-1
+while (backIndex > 0) {
+    let cursor = 0;
+    let idCount = 1;
+    while (fragmented[backIndex-idCount] === fragmented[backIndex]) {
+        idCount++;
+    }
+    let dotCount = 0
+    while (dotCount < idCount && cursor+idCount < backIndex){
+        while (fragmented[cursor] !== ".") {
+            cursor++;
+        }
+        dotCount = 1;
+        while (fragmented[cursor+dotCount] === ".") {
+            dotCount++;
+        }
+        if (dotCount < idCount) {
+            cursor++
+        }
+    }
+    if (dotCount >= idCount && cursor <backIndex) {
+        for (let j = 0; j < idCount; j++) {
+            fragmented[cursor+j] = fragmented[backIndex-j];
+            fragmented[backIndex-j] = "."
+        }
+    } else {
+        backIndex -= idCount;
+    }
+    while (fragmented[backIndex] === ".") {
+        backIndex--
+    }
+}
+checksum = 0;
+for (let i = 0; i < fragmented.length; i++) {
+    if (fragmented[i] !== ".") {
+        checksum += i * Number(fragmented[i])
+    }
+}
+console.log(checksum)