added day 18

.vscode/settings.json

@@ -3,6 +3,7 @@
         "aadamw",
         "Allis",
         "anthonyshew",
+        "arguemnt",
         "ayrock",
         "ayush",
         "basokant",

Day18/description.md

@@ -0,0 +1,14 @@
+# Santa's Remaining Deliveries
+
+Santa needs your help to count the number of presents he has to deliver! He's got all kinds of presents, from video game consoles (🎮), stuffed animals (🧸), toy cars (🏎️), books (📚), and more!
+
+We need a general purpose type that can take a tuple of items as its first arguemnt and an item to search for as the second argument. It should return a count of the item specified.
+
+For example:
+
+```ts
+Count<["👟", "👟", "💻", "🎸", "🧩", "👟", "🧸"], "👟">;
+```
+
+should return `3` because there are three `👟`.
+prompt by [Dimitri Mitropoulos](https://github.com/dimitropoulos) of [MiTS](https://www.youtube.com/@MichiganTypeScript)

Day18/solution.ts

@@ -0,0 +1,11 @@
+type Count<
+  List extends any[],
+  Target extends string,
+  Accumulator extends any[] = []
+> = List extends [infer Current, ...infer Rest]
+  ? Current extends Target
+    ? Count<Rest, Target, [...Accumulator, Current]>
+    : Count<Rest, Target, [...Accumulator]>
+  : Accumulator["length"];
+
+export { Count };

Day18/test.ts

@@ -0,0 +1,125 @@
+import { Expect, Equal } from "type-testing";
+import { Count } from "./solution";
+
+type ToySack = [
+  "🎸",
+  "🎧",
+  "👟",
+  "👟",
+  "💻",
+  "🪀",
+  "🧩",
+  "🎮",
+  "🎨",
+  "🕹️",
+  "📱",
+  "🧩",
+  "🧸",
+  "🎧",
+  "👟",
+  "🚲",
+  "📚",
+  "⌚",
+  "🎨",
+  "👟",
+  "🎸",
+  "🧸",
+  "👟",
+  "🎸",
+  "📱",
+  "🎧",
+  "🎮",
+  "🎒",
+  "📱",
+  "🧩",
+  "🧩",
+  "🚲",
+  "🕹️",
+  "🧵",
+  "📱",
+  "🕹️",
+  "🕰️",
+  "🧢",
+  "🕹️",
+  "👟",
+  "🧸",
+  "📚",
+  "🧁",
+  "🧩",
+  "🎸",
+  "🎮",
+  "🧁",
+  "📚",
+  "💻",
+  "⌚",
+  "🛹",
+  "🧁",
+  "🧣",
+  "🪁",
+  "🎸",
+  "🧸",
+  "🧸",
+  "🧸",
+  "🧩",
+  "🪁",
+  "🏎️",
+  "🏎️",
+  "🧁",
+  "📚",
+  "🧸",
+  "🕶️",
+  "💻",
+  "⌚",
+  "⌚",
+  "🕶️",
+  "🎧",
+  "🎧",
+  "🎧",
+  "💻",
+  "👟",
+  "🎸",
+  "💻",
+  "🪐",
+  "📚",
+  "🎨",
+  "📱",
+  "🎧",
+  "📱",
+  "🎸",
+  "🏎️",
+  "👟",
+  "🚲",
+  "📱",
+  "🚲",
+  "🎸"
+];
+
+type test_0_actual = Count<ToySack, "👟">;
+//   ^?
+type test_0_expected = 8;
+type test_0 = Expect<Equal<test_0_expected, test_0_actual>>;
+
+type test_1_actual = Count<ToySack, "🧦">;
+//   ^?
+type test_1_expected = 0;
+type test_1 = Expect<Equal<test_1_expected, test_1_actual>>;
+
+type test_2_actual = Count<ToySack, "🧩">;
+//   ^?
+type test_2_expected = 6;
+type test_2 = Expect<Equal<test_2_expected, test_2_actual>>;
+
+type test_3_actual = Count<ToySack, "🛹">;
+//   ^?
+type test_3_expected = 1;
+type test_3 = Expect<Equal<test_3_expected, test_3_actual>>;
+
+type test_4_actual = Count<ToySack, "🏎️">;
+//   ^?
+type test_4_expected = 3;
+type test_4 = Expect<Equal<test_4_expected, test_4_actual>>;
+
+type test_5_actual = Count<ToySack, "📚">;
+//   ^?
+type test_5_expected = 5;
+type test_5 = Expect<Equal<test_5_expected, test_5_actual>>;