Day 5

day5/part1.ts

@@ -0,0 +1,27 @@
+export async function solve() {
+    const [rules, pages] = await Deno.readTextFile("./input.txt")
+        .then(i => i
+            .split("\n\n")
+        ).then(([rules, pages]) => [
+            rules.split("\n").map(e => e.split("|") as [string, string]),
+            pages.split("\n").map(e => e.split(","))
+        ] as const);
+    
+    let sum = 0;
+
+    for (const pageGroup of pages) {
+        let valid = true;
+        for (let i = 1; i < pageGroup.length; i++) {
+            const matchingRules = rules.filter(([before, _]) => before == pageGroup[i]).filter(
+                ([before, _]) => before == pageGroup[i]
+            ).map(([_, after]) => after);
+            if (matchingRules.some(after => pageGroup.slice(0, i).includes(after))) {
+                valid = false;
+                break
+            }
+        }
+        if (valid) sum += +pageGroup[Math.floor(pageGroup.length / 2)];
+    }
+
+    return sum
+}

day5/part2.ts

@@ -0,0 +1,46 @@
+function sort(rules: [string, string][], pageGroup: string[]) {
+    let [valid, error] = validate(rules, pageGroup);
+    while (!valid) {
+        const tmp = pageGroup[error![0]];
+        pageGroup[error![0]] = pageGroup[error![1]];
+        pageGroup[error![1]] = tmp;
+
+        [valid, error] = validate(rules, pageGroup);
+    }
+}
+
+function validate(rules: [string, string][], pageGroup: string[]): [boolean, null | [number, number]] {
+    for (let i = 1; i < pageGroup.length; i++) {
+        const matchingRules = rules.filter(([before, _]) => before == pageGroup[i]).map(([_, after]) => after);
+        const error = matchingRules.find(after => pageGroup.slice(0, i).includes(after));
+        if (error !== undefined) {
+            return [false, [pageGroup.indexOf(error), i]];
+        }
+    }
+
+    return [true, null]
+}
+
+export async function solve() {
+    const [rules, pages] = await Deno.readTextFile("./input.txt")
+        .then(i => i
+            .split("\n\n")
+        ).then(([rules, pages]) => [
+            rules.split("\n").map(e => e.split("|") as [string, string]),
+            pages.split("\n").map(e => e.split(","))
+        ] as const);
+    
+    let sum = 0;
+
+    for (let pageGroup of pages) {
+        let [valid,error] = validate(rules, pageGroup);
+        if (valid !== true) {
+            // console.log(pageGroup, error);
+            sort(rules, pageGroup);
+
+            sum += +pageGroup[Math.floor(pageGroup.length / 2)];
+        };
+    }
+
+    return sum
+}