1 files changed, 58 insertions, 0 deletions
diff --git a/day02.lisp b/day02.lisp
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+(defun input-lines (f)
+  (with-open-file (s f)
+    (loop for line = (read-line s nil 'eof)
+          until (eq line 'eof)
+          collect line)))
+
+(defun check-set (string red green blue)
+  (multiple-value-bind (n begin)
+      (parse-integer string :junk-allowed t)
+    (cond ((search "red" string :start2 begin) (<= n red))
+          ((search "green" string :start2 begin) (<= n green))
+          ((search "blue" string :start2 begin) (<= n blue)))))
+
+(defun split-by-char (char string)
+  (loop for i = 0 then (1+ j)
+        as j = (position char string :start i)
+        collect (subseq string i j)
+        while j))
+
+(defun check-round (string red green blue)
+  (let ((sets (split-by-char #\, string)))
+    (not (find-if-not (lambda (set) (check-set set red green blue)) sets))))
+
+(defun check-game (string red green blue)
+  (let ((pstring (nth 1 (split-by-char #\: string))))
+    (let ((rounds (split-by-char #\; pstring)))
+      (not (find-if-not (lambda (set) (check-round set red green blue)) rounds)))))
+
+(defun solve1 (f)
+  (loop for line in (input-lines f)
+        as gid = (parse-integer line :junk-allowed t :start 5)
+        when (check-game line 12 13 14)
+          sum gid))
+
+(defun cube-count (string color)
+  (multiple-value-bind (n begin)
+      (parse-integer string :junk-allowed t)
+    (if (search color string :start2 begin) n 0)))
+
+(defun game-max-cubes (line color)
+  (loop for i = (1+ (position #\: line)) then (1+ j)
+        as j = (position-if (lambda (c) (or (equal c #\,) (equal c #\;))) line :start i)
+        as count = (cube-count (subseq line i j) color)
+        maximize count
+        while j))
+
+(defun solve2 (f)
+  (loop for line in (input-lines f)
+        as r = (game-max-cubes line "red")
+        as g = (game-max-cubes line "green")
+        as b = (game-max-cubes line "blue")
+        sum (* r g b)))
+
+(print (solve1 "data/02/example.txt"))
+(print (solve1 "data/02/input.txt"))
+(print (solve2 "data/02/example.txt"))
+(print (solve2 "data/02/input.txt"))
+