Add week 4 solutions: valid-palindrome

Author: gitsunmin

valid-palindrome/gitsunmin.ts

@@ -0,0 +1,14 @@
+/**
+ * https://leetcode.com/problems/valid-palindrome
+ * time complexity : O(n)
+ * space complexity : O(n)
+ */
+
+const clean = (s: string): string => s.toLowerCase().replace(/[^a-z0-9]/g, "");
+
+const reverse = (s: string): string => s.split("").reverse().join("");
+
+function isPalindrome(s: string): boolean {
+    const cleaned = clean(s);
+    return cleaned === reverse(cleaned);
+};