feat: add 6141-hard-binary-to-decimal

Author: coderhyy

type-challenges/6141-hard-binary-to-decimal/template.ts

@@ -0,0 +1,12 @@
+// 参考 https://github.com/type-challenges/type-challenges/issues/6985
+// 我不理解
+type ExpandTwo<T extends any[]> = [...T, ...T];
+
+type BinaryToDecimal<
+  S extends string,
+  R extends any[] = []
+> = S extends `${infer L}${infer Rest}`
+  ? L extends "0"
+    ? BinaryToDecimal<Rest, ExpandTwo<R>>
+    : BinaryToDecimal<Rest, [...ExpandTwo<R>, 0]>
+  : R["length"];

type-challenges/6141-hard-binary-to-decimal/test-cases.ts

@@ -0,0 +1,9 @@
+import type { Equal, Expect } from "@type-challenges/utils";
+
+type cases = [
+  Expect<Equal<BinaryToDecimal<"10">, 2>>,
+  Expect<Equal<BinaryToDecimal<"0011">, 3>>,
+  Expect<Equal<BinaryToDecimal<"00000000">, 0>>,
+  Expect<Equal<BinaryToDecimal<"11111111">, 255>>,
+  Expect<Equal<BinaryToDecimal<"10101010">, 170>>
+];