feat(day22): cut 3

Author: coderbyheart

day22/cardshuffle.spec.ts

@@ -1,8 +1,10 @@
-import { dealIntoNewStack } from './cardshuffle'
+import { dealIntoNewStack, cut } from './cardshuffle'
+
+const testDeck = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
 
 describe('Card Shuffle', () => {
 	test('deal 10 cards into a new deck', () => {
-		expect(dealIntoNewStack([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])).toEqual([
+		expect(dealIntoNewStack([...testDeck])).toEqual([
 			9,
 			8,
 			7,
@@ -15,4 +17,7 @@ describe('Card Shuffle', () => {
 			0,
 		])
 	})
+	test('cut 3', () => {
+		expect(cut(3)([...testDeck])).toEqual([3, 4, 5, 6, 7, 8, 9, 0, 1, 2])
+	})
 })

day22/cardshuffle.ts

@@ -1,3 +1,8 @@
-export const dealIntoNewStack = (deck: number[]): number[] => [
-	...deck.reverse(),
+type Deck = number[]
+
+export const dealIntoNewStack = (deck: Deck): Deck => [...deck.reverse()]
+
+export const cut = (n: number) => (deck: Deck): Deck => [
+	...deck.slice(n),
+	...deck.slice(0, n),
 ]