From a1c8126274d5cd60a385f85f5fd4027f97bbac6c Mon Sep 17 00:00:00 2001
From: Sijmen Schoon <s.j.schoon@student.utwente.nl>
Date: Thu, 9 Dec 2021 13:35:26 +0100
Subject: [PATCH] day 7

---
 .gitignore |  3 +++
 day07.scm  | 41 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 44 insertions(+)
 create mode 100644 day07.scm

diff --git a/.gitignore b/.gitignore
index 552b246..dd8443a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,5 @@
 *.in
 .metals/
+
+# binaries
+day??
diff --git a/day07.scm b/day07.scm
new file mode 100644
index 0000000..3ef763b
--- /dev/null
+++ b/day07.scm
@@ -0,0 +1,41 @@
+(import (chicken string))
+(import (chicken format))
+(import (chicken io))
+(import (chicken sort))
+(import (only traversal enumerate))
+(import srfi-1)
+(import srfi-14)
+(import srfi-60)
+(import srfi-141)
+
+(define numbers (map string->number (string-split (read-line) ",")))
+
+; PART 1
+(define sorted (sort numbers <))
+(define median (list-ref sorted (floor/ (length numbers) 2)))
+
+(define (part1)
+  (foldl
+   (lambda (x y) (+ x (abs (- y median))))
+   0
+   numbers))
+
+
+; PART 2
+(define (triangular n) (/ (* n (+ n 1)) 2))
+
+(define (part2- avg)
+  (foldl
+   (lambda (x y) (+ x (triangular (abs (- y avg)))))
+   0
+   numbers))
+
+(define avgCeil (ceiling/ (foldl + 0 numbers) (length numbers)))
+(define avgFloor (floor/ (foldl + 0 numbers) (length numbers)))
+
+(define (part2)
+  (min (part2- avgCeil) (part2- avgFloor)))
+
+
+(format #t "part 1: ~A~%" (part1))
+(format #t "part 2: ~A~%" (part2))