feat: add 0059-hard-get-optional

Author: coderhyy

type-challenges/0059-hard-get-optional/template.ts

@@ -0,0 +1,3 @@
+type GetOptional<T> = {
+  [K in keyof T as T[K] extends Required<T>[K] ? never : K]: T[K];
+};

type-challenges/0059-hard-get-optional/test-cases.ts

@@ -0,0 +1,8 @@
+import type { Equal, Expect } from "@type-challenges/utils";
+
+type cases = [
+  Expect<Equal<GetOptional<{ foo: number; bar?: string }>, { bar?: string }>>,
+  Expect<
+    Equal<GetOptional<{ foo: undefined; bar?: undefined }>, { bar?: undefined }>
+  >
+];