From 148867f294e0ab0906c22f186dc0357b0a53e896 Mon Sep 17 00:00:00 2001
From: MrSpoony <kimi.loeffel@hispeed.ch>
Date: Thu, 9 Mar 2023 09:11:03 +0100
Subject: [PATCH] add is palindrome

---
 is-palindrome.ts | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)
 create mode 100644 is-palindrome.ts

diff --git a/is-palindrome.ts b/is-palindrome.ts
new file mode 100644
index 0000000..10d06ad
--- /dev/null
+++ b/is-palindrome.ts
@@ -0,0 +1,32 @@
+import type { Equal, Expect } from '@type-challenges/utils'
+
+type casesPalindrome = [
+  Expect<Equal<IsPalindrome<'abc'>, false>>,
+  Expect<Equal<IsPalindrome<'b'>, true>>,
+  Expect<Equal<IsPalindrome<'abca'>, false>>,
+  Expect<Equal<IsPalindrome<'abcba'>, true>>,
+  Expect<Equal<IsPalindrome<121>, true>>,
+  Expect<Equal<IsPalindrome<19260817>, false>>,
+]
+
+type CheckPalindrome<
+    T extends string[]
+> = 
+T extends [infer First, ...infer Mid, infer Last]
+    ? First extends Last
+        ? Mid extends string[] ? CheckPalindrome<Mid> : never
+        : false
+    : true
+;
+
+type ToArr<T extends string> = T extends `${infer Head}${infer Tail}` ? [Head, ...ToArr<Tail>] : [];
+
+type IsPalindrome<
+    T extends string | number
+> = 
+T extends number
+    ? IsPalindrome<`${T}`>
+: T extends string
+    ? CheckPalindrome<ToArr<T>>
+: never
+