add maximum

maximum.ts

@@ -0,0 +1,32 @@
+import type { Equal, Expect } from '@type-challenges/utils'
+
+type cases = [
+  Expect<Equal<Maximum<[]>, never>>,
+  Expect<Equal<Maximum<[0, 2, 1]>, 2>>,
+  Expect<Equal<Maximum<[1, 20, 200, 150]>, 200>>,
+]
+
+type Max<
+  T extends number,
+  U extends number,
+  Acc extends 1[] = []
+> =
+Acc['length'] extends T
+  ? U
+  : Acc['length'] extends U
+    ? T
+    : Max<T, U, [...Acc, 1]>
+
+type Maximum<
+  T extends unknown[]
+> =
+T extends [infer First, infer Second, ...infer Tail]
+  ? First extends number
+    ? Second extends number
+      ? Maximum<[Max<First, Second>, ...Tail]>
+      : never
+    : never
+  : T extends [infer Head, ...infer Tail]
+    ? T[0]
+    : never
+;