1 files changed, 20 insertions, 1 deletions
diff --git a/day6/index.ts b/day6/index.ts
index 612aebf..1b9e69f 100644
--- a/day6/index.ts
+++ b/day6/index.ts
@@ -4,12 +4,24 @@ import { ExerciseModuleFunc } from "../types";
 
 type Group = string[];
 
+const intersection = <T extends unknown>(a: Set<T>, b: Set<T>) =>
+  new Set(Array.from(a).filter(x => b.has(x)));
+
 const getUniq = (group: Group): Set<string> => {
   const joined = group.join("").split("");
   const set = new Set(joined);
   return set;
 }
 
+const getIntersection = (group: Group): Set<string> => {
+  let result = new Set(group[0]);
+  for (let i = 1; i < group.length; i += 1) {
+    const set = new Set(group[i]);
+    result = intersection(result, set);
+  }
+  return result;
+}
+
 const day6: ExerciseModuleFunc = async (input: string) => {
   const splitted = input.split("\n\n");
   const groups: Group[] = splitted.map(g => g.split("\n"));
@@ -23,7 +35,14 @@ const day6: ExerciseModuleFunc = async (input: string) => {
     reduce((acc, val) => acc + val)
   ).toPromise();
 
-  return Promise.all([prom1]);
+  const prom2 = of(groups).pipe(
+    concatAll(),
+    map(getIntersection),
+    map(res => res.size),
+    reduce((acc, val) => acc + val)
+  ).toPromise();
+
+  return Promise.all([prom1, prom2]);
 }
 
 export default day6;