Finished problem 4 of 2015 in racket

2015/puzzle-4.rkt

@@ -0,0 +1,20 @@
+#lang racket
+
+(require racket/file)
+(require file/md5)
+
+(define input (file->string "4-input"))
+
+(define (find-salt requested-string current)
+  (let* ([full-message (string-append input (number->string current))]
+         [hash (bytes->string/locale (md5 full-message))])
+    (if (string-prefix? hash requested-string)
+        current
+        (find-salt requested-string (+ current 1)))))
+
+(printf "Round 1: ~a~%" (find-salt "00000"  0))
+(printf "Round 2: ~a~%" (find-salt "000000" 0))
+
+;; Local Variables:
+;; compile-command: "racket puzzle-4.rkt"
+;; End: