1 files changed, 16 insertions, 0 deletions
diff --git a/2015/day-25/day-25.rkt b/2015/day-25/day-25.rkt
new file mode 100644
index 0000000..786538c
--- /dev/null
+++ b/2015/day-25/day-25.rkt
@@ -0,0 +1,16 @@
+#lang racket
+
+(define max-r 2978)
+(define max-c 3083)
+
+(for/fold ([code 20151125]
+           [r 1]
+           [c 1])
+          ([i (in-naturals)]
+           #:break (and (= max-r r)
+                        (= max-c c)))
+  (define new-code
+    (modulo (* code 252533) 33554393))
+  (if (= r 1)
+      (values new-code (add1 c) 1)
+      (values new-code (sub1 r) (add1 c))))