1 files changed, 104 insertions, 0 deletions
diff --git a/day7/index.ts b/day7/index.ts
new file mode 100644
index 0000000..f6a126e
--- /dev/null
+++ b/day7/index.ts
@@ -0,0 +1,104 @@
+import { of } from "rxjs";
+import { concatAll, map, reduce, toArray } from 'rxjs/operators';
+import { ExerciseModuleFunc } from "../types";
+
+interface RuleChild {
+  type: string;
+  num: number;
+}
+
+interface Rule {
+  type: string;
+  children: RuleChild[];
+}
+
+interface TreeNode {
+  type: string;
+  children: TreeNode[];
+}
+
+const union = <T extends unknown>(...sets: Set<T>[]): Set<T> => {
+  let result = new Set<T>();
+  for (const set of sets) {
+    result = new Set([...Array.from(result), ...Array.from(set)]);
+  }
+  return result;
+}
+
+const rowToRule = (row: string): Rule => {
+  const [lhs, rhs] = row.split("bags contain").map(part => part.trim());
+
+  if (rhs.startsWith("no")) {
+    return {
+      type: lhs,
+      children: []
+    }
+  }
+
+  const childBags = rhs.split(", ");
+  const children = childBags.map(str => {
+    const match = str.match(/(\d)\ (\w+\ \w+).*?/);
+
+    const num = Number(match[1]);
+    const type = match[2];
+
+    return {
+      type,
+      num
+    }
+  });
+
+  return {
+    type: lhs,
+    children
+  }
+};
+
+const constructNode = (rules: Rule[], type: string): TreeNode => {
+  const children = rules
+    .filter(rule => rule.children.some(child => child.type === type))
+    .reduce((acc: TreeNode, rule) => {
+      const newChild = constructNode(rules, rule.type);
+      acc.children.push(newChild);
+      return acc;
+    }, { type, children: [] });
+
+  return children;
+}
+
+const buildTree = (rules: Rule[], rootType: string) => {
+  return constructNode(rules, rootType);
+}
+
+const uniqueNonRootNodes = (tree: TreeNode): Set<string> => {
+  let set = new Set<string>();
+
+  for (let child of tree.children) {
+    set.add(child.type);
+
+    const childUniques = uniqueNonRootNodes(child);
+    set = union(set, childUniques);
+  }
+
+  return set;
+}
+
+const day7: ExerciseModuleFunc = async (input: string) => {
+  const rows = input.split("\n");
+
+  const prom1 = of(rows).pipe(
+    concatAll(),
+    map(rowToRule),
+    toArray(),
+    map(rules => buildTree(rules, "shiny gold")),
+    map(tree => uniqueNonRootNodes(tree)),
+    map(set => set.size)
+  ).toPromise();
+
+  // const prom2 = of(rows).pipe(
+  // ).toPromise();
+
+  return Promise.all([prom1]);
+}
+
+export default day7;