4 Largest Palindrome Product

1 files changed, 14 insertions, 0 deletions

diff --git a/0004/main.lisp b/0004/main.lisp
new file mode 100644
index 0000000..8874489
--- /dev/null
+++ b/0004/main.lisp
@@ -0,0 +1,14 @@
+(defun find-palindrome-impl (i j current-max)
+    (cond ((> j 999) current-max)
+	  ((> i 999) (find-palindrome-impl 100 (+ j 1) current-max))
+	  ((is-palindrome (* i j))
+	   (if (> (* i j) current-max)
+	       (find-palindrome-impl (+ i 1) j (* i j))
+	       (find-palindrome-impl (+ i 1) j current-max)))
+	  (t (find-palindrome-impl (+ i 1) j current-max))))
+
+(defun is-palindrome (x)
+  (equal (reverse (write-to-string x)) (write-to-string x)))
+
+
+(format t "~&~S~%" (find-palindrome-impl 100 100 0))