15

15.1.ts

@@ -15,4 +15,5 @@ const file = await open('./inputs/15');
 
 for await (const line of file.readLines()) {
     console.log(line.split(',').map(getHash).reduce((acc, cur) => acc + cur, 0))
-}
+}
+console.log(getHash('rn'))

15.2.ts

@@ -0,0 +1,52 @@
+import { open } from 'node:fs/promises';
+
+function getHash(input: string) {
+    let curr = 0
+
+    for (var i = 0; i < input.length; i++) {
+        curr += input.charCodeAt(i)
+        curr *= 17
+        curr %= 256
+    }
+    return curr
+}
+
+const boxes = new Array(256).fill([]).map(() => new Array()) as { label: string, focal: number }[][]
+const file = await open('./inputs/15');
+
+for await (const line of file.readLines()) {
+
+
+    const lenses = line.split(',')
+    lenses.forEach(l => {
+        // Remove
+        if (l.endsWith('-')) {
+            const label = l.slice(0, l.length - 1)
+            const box = getHash(label)
+            const index = boxes[box].findIndex(e => e.label === label)
+            if (index == -1) {
+                return
+            }
+            boxes[box].splice(index, 1)
+        }
+
+        // Add or Replace
+        if (l.indexOf('=') !== -1) {
+            const [label, focal] = l.split('=')
+            const box = getHash(label)
+            const index = boxes[box].findIndex(e => e.label === label)
+            if (index == -1) {
+                boxes[box].push({ label, focal: Number(focal) })
+            } else {
+                boxes[box][index].focal = Number(focal)
+            }
+        }
+    })
+}
+
+const score = boxes.reduce((prev, box, boxIndex) =>
+    box.reduce((acc, lens, slot) =>
+        (boxIndex + 1) * (slot + 1) * lens.focal + acc
+        , 0) + prev
+    , 0)
+console.log(score)