Add '2020/' from commit 'aaabfa90c9033044d0a9d5fe6776b718711ef46c'

git-subtree-dir: 2020
git-subtree-mainline: ab8f135946
git-subtree-split: aaabfa90c9

2020/07/part2.js

@@ -0,0 +1,42 @@
+const fs = require('fs');
+const OWN_BAG = 'shiny gold';
+
+function parseLine(line) {
+  let [ self, others ] = line.trim().split(" bags contain ");
+  if (self === undefined || others === undefined) return [];
+  if (others == "no other bags.") return []; // [{a: self, b: null, count: 0}];
+  others = others.replace(".", "").replace(/bags?/g, "").split(",");
+
+  return  others.map((other) => {
+    let [ num, ...rest ] = other.trim().split(' ');
+    return { a: self, b: rest.join(' '), count: Number(num) };
+  });
+}
+
+fs.readFile('input', (err, data) => {
+  if (err) throw err;
+  let rules = data.toString().split("\n").map( parseLine ).flat();
+
+  let bags = {};
+  rules.forEach((rule) => {
+    let parent = bags[rule.a] || {spec: rule.a};
+    let child = bags[rule.b] || {spec: rule.b};
+
+    if (!child.hasOwnProperty('parent')) child.parent = parent;
+    if (!parent.hasOwnProperty('children')) parent.children = [];
+    parent.children.push({ count: rule.count, bag: child });
+
+    bags[rule.a] = parent;
+    bags[rule.b] = child;
+  });
+
+  let bagCount = function(bag, self_count) {
+    if (!bag.children) return self_count;
+    return self_count + (bag.children.map((node) => bagCount(node.bag, node.count)).reduce((a,b) => a+b) * self_count);
+  };
+
+  let result = bags[OWN_BAG].children.map((node) => bagCount(node.bag, node.count)).reduce((a,b) => (a+b));
+
+  console.log(result);
+});
+