Day 5

05/part1.js

@@ -0,0 +1,49 @@
+const { readFileSync } = require("fs");
+// Parse Input
+const inputFile = "input.txt";
+const input = readFileSync(inputFile).toString();
+const rules = [];
+const updates = [];
+
+input.split("\n").forEach((line) => {
+  if (line.includes("|")) {
+    rules.push(line.split("|").map((x) => parseInt(x)));
+  } else if (line.includes(",")) {
+    updates.push(line.split(",").map((x) => parseInt(x)));
+  }
+});
+
+function checkRule(rule, update) {
+  const n1 = update.indexOf(rule[0]);
+  const n2 = update.indexOf(rule[1]);
+
+  return n1 == -1 || n2 == -1 || n1 < n2;
+}
+
+function findRulesForNumber(number) {
+  const result = [];
+  rules.forEach((r) => {
+    if (r.includes(number)) result.push(r);
+  });
+
+  return result;
+}
+
+const valid = [];
+updates.forEach((u) => {
+  let isValid = true;
+  u.forEach((n) => {
+    findRulesForNumber(n).forEach((r) => {
+      if (!checkRule(r, u)) isValid = false;
+    });
+  });
+
+  if (isValid) valid.push(u);
+});
+
+let result = 0;
+valid.forEach((u) => {
+  result += u[(u.length / 2) >> 0];
+});
+
+console.log(result);

05/part2.js

@@ -0,0 +1,70 @@
+const { readFileSync } = require("fs");
+// Parse Input
+const inputFile = "input.txt";
+const input = readFileSync(inputFile).toString();
+const rules = [];
+const updates = [];
+
+input.split("\n").forEach((line) => {
+  if (line.includes("|")) {
+    rules.push(line.split("|").map((x) => parseInt(x)));
+  } else if (line.includes(",")) {
+    updates.push(line.split(",").map((x) => parseInt(x)));
+  }
+});
+
+function applyRule(rule, update) {
+  const n1 = update.indexOf(rule[0]);
+  const n2 = update.indexOf(rule[1]);
+
+  if (n1 == -1 || n2 == -1 || n1 < n2) {
+    return;
+  }
+
+  let newUpdate = update;
+  let temp = newUpdate[n2];
+  newUpdate[n2] = newUpdate[n1];
+  newUpdate[n1] = temp;
+
+  return newUpdate;
+}
+
+function findRulesForNumber(number) {
+  const result = [];
+  rules.forEach((r) => {
+    if (r.includes(number)) result.push(r);
+  });
+
+  return result;
+}
+
+const invalid = [];
+updates.forEach((u) => {
+  let currentUpdate = u;
+  let updated = false;
+  let modified = true;
+  while (modified) {
+    modified = false;
+    currentUpdate.forEach((n) => {
+      findRulesForNumber(n).forEach((r) => {
+        const fixed = applyRule(r, currentUpdate);
+        if (fixed) {
+          currentUpdate = fixed;
+          updated = true;
+          modified = true;
+        }
+      });
+    });
+  }
+
+  if (updated) {
+    invalid.push(currentUpdate);
+  }
+});
+
+let result = 0;
+invalid.forEach((u) => {
+  result += u[(u.length / 2) >> 0];
+});
+
+console.log(result);