solve day 15 part 1

1 files changed, 19 insertions, 0 deletions

diff --git a/15/1.rkt b/15/1.rkt
new file mode 100644
index 0000000..448a10e
--- /dev/null
+++ b/15/1.rkt
@@ -0,0 +1,19 @@
+#lang racket
+
+(define line
+  (call-with-input-file "input"
+    (λ (fp) (read-line fp))))
+
+(define strs (string-split line ","))
+
+(define (calc-hash str)
+  (define len (string-length str))
+  (let loop ((i 0) (cur 0))
+    (if (< i len)
+      (let ()
+        (define c (string-ref str i))
+        (define ascii (char->integer c))
+        (loop (+ i 1) (modulo (* 17 (+ cur ascii)) 256)))
+      cur)))
+
+(apply + (map calc-hash strs))
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