feat: 2020/6

Add day 6 of 2020

2020/day/6/index.test.ts

@@ -0,0 +1,25 @@
+import { readFileSync } from 'fs';
+import { part1, part2 } from '.';
+
+const input = readFileSync(`${__dirname}/input`, 'utf-8').split('\n\n');
+const sampleInput = readFileSync(`${__dirname}/input.sample`, 'utf-8').split('\n\n');
+
+describe('Day 6', () => {
+  describe('Part 1', () => {
+    it('should return count of some answers', () => {
+      expect.assertions(2);
+
+      expect(part1(sampleInput)).toStrictEqual(11);
+      expect(part1(input)).toStrictEqual(6161);
+    });
+  });
+
+  describe('Part 2', () => {
+    it('should return count of all answers', () => {
+      expect.assertions(2);
+
+      expect(part2(sampleInput)).toStrictEqual(6);
+      expect(part2(input)).toStrictEqual(2971);
+    });
+  });
+});

2020/day/6/index.ts

@@ -0,0 +1,33 @@
+function union<T>(a: Set<T>, b: Set<T>): Set<T> {
+  return new Set([...a, ...b]);
+}
+
+function intersection<T>(a: Set<T>, b: Set<T>): Set<T> {
+  return new Set([...a].filter((element) => b.has(element)));
+}
+
+function part1(groups: string[]): number {
+  return groups.reduce(
+    (totalGroups, group) =>
+      totalGroups +
+      group
+        .split('\n')
+        .map((person) => new Set(person))
+        .reduce((totalPeople, person) => union(totalPeople, new Set(person))).size,
+    0,
+  );
+}
+
+function part2(groups: string[]): number {
+  return groups.reduce(
+    (totalGroups, group) =>
+      totalGroups +
+      group
+        .split('\n')
+        .map((person) => new Set(person))
+        .reduce((totalPeople, person) => intersection(totalPeople, new Set(person))).size,
+    0,
+  );
+}
+
+export { part1, part2 };