adding old leetcode solutions

1 files changed, 12 insertions, 0 deletions

diff --git a/leetcode/lc-125-valid-palindrome.rkt b/leetcode/lc-125-valid-palindrome.rkt
new file mode 100644
index 0000000..ed91d08
--- /dev/null
+++ b/leetcode/lc-125-valid-palindrome.rkt
@@ -0,0 +1,12 @@
+#lang racket
+
+(define/contract (is-palindrome s)
+  (-> string? boolean?)
+  (define clean-string
+    (string-downcase (string-replace s #rx"[^A-Za-z0-9]" "")))
+  (string-prefix? (apply string-append (map string (reverse (string->list clean-string))))
+                  (substring clean-string
+                             0
+                             (ceiling (/ (string-length clean-string) 2)))))
+
+(is-palindrome "A man, a plan, a canal: Panama")
\ No newline at end of file