Day 6 & 7

2024/05/index2.ts

@@ -0,0 +1,42 @@
+const fs = require('fs');
+
+const input = fs.readFileSync(__dirname + '/input.txt', 'utf8');
+
+const rules: Array<[number, number]> = [];
+const updates: Array<Array<number>> = [];
+
+let rulesSection = true;
+input.split("\n").forEach((line: string) => {
+    if (!line) {
+        rulesSection = false;
+        return;
+    }
+    if (rulesSection) {
+        rules.push(line.split('|').map((s) => parseInt(s)) as [number, number]);
+    } else {
+        updates.push(line.split(',').map((s) => parseInt(s)));
+    }
+});
+
+let result = 0;
+
+updates.forEach((update) => {
+    let newUpdate: Array<number> = [];
+    for (let page of update) {
+        const relevantRules = rules.filter((rule) => rule[0] === page || rule[1] === page);
+        let i = 0;
+        for (; i < newUpdate.length; i++) {
+            const otherPage = newUpdate[i];
+            const rule = relevantRules.find((rule) => rule[0] === otherPage || rule[1] === otherPage);
+            if (rule && rule[0] === page) {
+                break;
+            }
+        }
+        newUpdate = [...newUpdate.slice(0, i), page, ...newUpdate.slice(i)]
+    }
+    if (update.join(',') !== newUpdate.join(',')) {
+        result += newUpdate[(newUpdate.length - 1) / 2];
+    }
+});
+
+console.log(result);