aboutsummaryrefslogtreecommitdiff
path: root/2022/puzzle-2.lisp
diff options
context:
space:
mode:
authorAryadev Chavali <aryadev@aryadevchavali.com>2023-06-26 08:35:43 +0100
committerAryadev Chavali <aryadev@aryadevchavali.com>2023-06-26 08:36:53 +0100
commitc0964cbb42710129a217e84bf7525f68f3fd670e (patch)
treefaa7e762fb747342c44c9852eee84ec7e3f2860a /2022/puzzle-2.lisp
parent29cacf2394a6d64f1ab3d5ba13a35f3beb08c3c7 (diff)
downloadadvent-of-code-c0964cbb42710129a217e84bf7525f68f3fd670e.tar.gz
advent-of-code-c0964cbb42710129a217e84bf7525f68f3fd670e.tar.bz2
advent-of-code-c0964cbb42710129a217e84bf7525f68f3fd670e.zip
(*->2022)~made it clear what advent of code I'm doing
Diffstat (limited to '2022/puzzle-2.lisp')
-rw-r--r--2022/puzzle-2.lisp54
1 files changed, 54 insertions, 0 deletions
diff --git a/2022/puzzle-2.lisp b/2022/puzzle-2.lisp
new file mode 100644
index 0000000..b3b0155
--- /dev/null
+++ b/2022/puzzle-2.lisp
@@ -0,0 +1,54 @@
+(defvar input (uiop:read-file-string "2022/2-input"))
+;; Each newline represents a new round, which we should parse on the go
+
+(defun sensible-convert-input (str)
+ (cond
+ ((or (string= str "X") (string= str "A")) 0)
+ ((or (string= str "Y") (string= str "B")) 1)
+ ((or (string= str "Z") (string= str "C")) 2)))
+
+;; Round 1
+(defvar rounds
+ (with-input-from-string (stream input)
+ (loop
+ for strategy = (read-line stream nil)
+ until (null strategy)
+ collect
+ (let ((opponent (subseq strategy 0 1))
+ (yours (subseq strategy 2 3)))
+ (list (sensible-convert-input opponent) (sensible-convert-input yours))))))
+
+(loop
+ for round in rounds
+ until (null round)
+ sum
+ (destructuring-bind (opp you) round
+ (+
+ 1 you ;; base score
+ (cond ; outcome score
+ ((eq you opp) 3)
+ ((eq (mod (+ 1 opp) 3) you) 6)
+ (t 0)))))
+
+;; Round 2.
+
+;; We can still use the same rounds data as previously, just
+;; reinterpret it in when doing the sum.
+
+(defun get-correct-choice (opponent outcome)
+ (case outcome
+ (0 (mod (- opponent 1) 3))
+ (1 opp)
+ (2 (mod (+ 1 opponent) 3))
+ (t 0)))
+
+(loop for round in rounds
+ sum
+ (destructuring-bind (opp you) round
+ (let ((choice (get-correct-choice opp you)))
+ (+ 1 choice
+ (case you ;; outcome -> score
+ (0 0)
+ (1 3)
+ (2 6)
+ (t 0))))))