adventofcode2022

commit a42c098253c0b4a234ebc0444cc100e19fdfa9c0
parent 904fe53545fc791e4a7ad69b514b0c06bf7fa583
Author: Lukas Henkel <lh@entf.net>
Date:   Sat,  3 Dec 2022 09:38:54 +0100

Day 3 task 2

Diffstat:
M
src/day03.lisp
 | 
52
+++++++++++++++++++++++++++++++++++++++-------------
M
t/day03.lisp
 | 
5
+++++

2 files changed, 44 insertions(+), 13 deletions(-)
diff --git a/src/day03.lisp b/src/day03.lisp
@@ -2,29 +2,55 @@
   (:use #:cl #:adventofcode2022))
 (in-package #:adventofcode2022/day03)
 
+(defun calculate-priority (result)
+  (if (char>= result #\a)
+      (- (char-code result) 96)
+      (- (char-code result) 38)))
+
 (defun task1 (inputs)
   (loop for input in inputs
-        sum (let ((compartment1 (car input))
-                  (compartment2 (cdr input))
-                  (result))
+        sum (let* ((compartment-size (/ (length input) 2))
+                   (compartment1 (subseq input 0 compartment-size))
+                   (compartment2 (subseq input compartment-size))
+                   (result))
               (loop for item1 across compartment1
                     for item2 across compartment2
-                    when (find item1 compartment2 :test #'equal)
+                    when (find item1 compartment2)
                       do (progn
                            (setf result item1)
                            (loop-finish))
-                    when (find item2 compartment1 :test #'equal)
+                    when (find item2 compartment1)
                       do (progn
                            (setf result item2)
                            (loop-finish)))
-              (if (char>= result #\a)
-                  (- (char-code result) 96)
-                  (- (char-code result) 38)))))
+              (calculate-priority result))))
+
+(defun all-chars-from-to (from to)
+  (loop for i from (char-code from) to (char-code to)
+        collect (code-char i)))
+
+(defun task2 (inputs)
+  (let* ((items (concatenate 'list
+                             (all-chars-from-to #\A #\Z)
+                             (all-chars-from-to #\a #\z)))
+         (group)
+         (groups (loop for i from 1
+                       for elf in inputs
+                       do (push elf group)
+                       when (= (mod i 3) 0)
+                         collect group and do (setf group nil))))
+    (loop for group in groups
+          sum (let ((result))
+                (loop for item in items
+                      when (= 0 (length (remove-if (lambda (elf)
+                                                     (find item elf))
+                                                   group)))
+                        do (progn
+                             (setf result item)
+                             (loop-finish)))
+                (calculate-priority result)))))
 
 (define-day 3
-    (:translate-input (lambda (line)
-                        (let ((compartment-size (/ (length line) 2)))
-                          (cons (subseq line 0 compartment-size)
-                                (subseq line compartment-size)))))
+    ()
   #'task1
-  nil)
+  #'task2)
diff --git a/t/day03.lisp b/t/day03.lisp
@@ -13,3 +13,8 @@ CrZsJsPPZsGzwwsLwLmpwMDw")
       (run-task 3 1
                 (make-string-input-stream +testdata-day03+)))))
 
+(def-test day03-task2 ()
+  (is-true
+   (= 70
+      (run-task 3 2
+                (make-string-input-stream +testdata-day03+)))))