day 5

2024/5.2.ts

@@ -0,0 +1,77 @@
+import { open } from "node:fs/promises";
+
+const file = await open("./2024/inputs/5");
+
+const rules: { [key: number]: number[] } = {}
+const prints: string[][] = []
+for await (const line of file.readLines()) {
+    if (line.includes("|")) {
+        const index = Number(Array.from(line.matchAll(/(\d+)\|(\d+)/gm))[0][1])
+        const value = Number(Array.from(line.matchAll(/(\d+)\|(\d+)/gm))[0][2])
+        if (!(index in rules)) {
+            rules[index] = []
+        }
+        rules[index].push(value)
+    } else if (line.includes(',')) {
+        prints.push(line.split(","))
+    }
+}
+
+function print_to_indexes(print: string[]) {
+    const order: { [key: string]: number } = {}
+    print.forEach((v, i) => {
+        order[Number(v)] = i
+    })
+    return order
+}
+function check_rules(rules: { [key: number]: number[] }, print_indexes: { [key: number]: number }) {
+    for (const [key, vs] of Object.entries(rules)) {
+        for (const value of vs) {
+            if (!(Number(key) in print_indexes) || !(value in print_indexes)) {
+                continue
+            }
+            if (print_indexes[Number(key)] < print_indexes[value]) {
+                continue
+            }
+            return false
+        }
+
+    }
+    return true
+}
+
+
+const prints_filtered = prints.filter(p => !check_rules(rules, print_to_indexes(p)))
+
+const prints_reordered = []
+for (const p of prints_filtered) {
+    const current_list: number[] = []
+    for (const page of p) {
+
+        if (current_list.length == 0) {
+            current_list.push(Number(page))
+            continue
+        }
+
+        if (page in rules) {
+            let target_index = Infinity
+            for (const e of rules[Number(page)]) {
+                if (current_list.indexOf(e) > -1) {
+                    target_index = Math.min(current_list.indexOf(e), target_index)
+                }
+            }
+            current_list.splice(target_index, 0, Number(page))
+        } else {
+            current_list.push(Number(page))
+        }
+    }
+    prints_reordered.push(current_list)
+}
+
+prints_reordered.reduce((prev, curr) => {
+    return prev + curr[Math.floor(curr.length / 2)]
+}, 0)
+
+console.log(prints_reordered.reduce((prev, curr) => {
+    return prev + curr[Math.floor(curr.length / 2)]
+}, 0))