1 files changed, 52 insertions, 0 deletions
diff --git a/day4/index.ts b/day4/index.ts
new file mode 100644
index 0000000..1d059dc
--- /dev/null
+++ b/day4/index.ts
@@ -0,0 +1,52 @@
+import { Observable, of } from "rxjs";
+import { concatAll, count, filter, groupBy, map, mergeMap, reduce, tap } from 'rxjs/operators';
+import { ExerciseModuleFunc } from "../types";
+
+interface Passport {
+  byr: string;
+  iyr: string;
+  eyr: string;
+  hgt: string;
+  hcl: string;
+  ecl: string;
+  pid: string;
+  cid?: string;
+}
+
+const parsePassports = (input: string): Passport[] => {
+  const sections = input.split("\n\n")
+  const splitted = sections.map(s => s.split(/[\n\r\s]+/g));
+
+  const result = splitted.map(s => s.reduce((acc, val) => {
+    const [lhs, rhs] = val.split(":");
+    acc[lhs] = rhs;
+    return acc;
+  }, {})) as Passport[];
+
+  return result;
+}
+
+const isPassportValid = (passport: Passport): boolean => {
+  const requiredKeys = ["byr", "iyr", "eyr", "hgt", "hcl", "ecl", "pid"];
+
+  let valid = true;
+  requiredKeys.forEach(key => {
+    if (passport[key] === undefined) {
+      valid = false;
+    }
+  });
+  return valid;
+}
+
+const day4: ExerciseModuleFunc = async (input: string) => {
+  const prom1 = of(input).pipe(
+    map(parsePassports),
+    concatAll(),
+    filter(isPassportValid),
+    count()
+  ).toPromise();
+
+  return Promise.all([prom1]);
+}
+
+export default day4;