adding old leetcode solutions

1 files changed, 17 insertions, 0 deletions

diff --git a/leetcode/lc-788-rotated-digits.rkt b/leetcode/lc-788-rotated-digits.rkt
new file mode 100644
index 0000000..79400b8
--- /dev/null
+++ b/leetcode/lc-788-rotated-digits.rkt
@@ -0,0 +1,17 @@
+#lang racket
+
+(define/contract (rotated-digits max-n)
+  (-> exact-integer? exact-integer?)
+  (for/fold ([good-number-count 0])
+            ([n (in-range 1 (add1 max-n))])
+    (if (is-good? n)
+        (add1 good-number-count)
+        good-number-count)))
+
+(define/contract (is-good? test-number)
+  (-> exact-integer? boolean?)
+  (define test-string (number->string test-number))
+  (match test-string
+    [(regexp #rx"^[018]*$") #false]
+    [(regexp #rx"^[0125689]*$") #true]
+    [_ #false]))
\ No newline at end of file