6614131d7b10

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/data/2021/11.txt	Mon Dec 13 12:42:30 2021 -0500
@@ -0,0 +1,10 @@
+2682551651
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--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/data/2021/12.txt	Mon Dec 13 12:42:30 2021 -0500
@@ -0,0 +1,20 @@
+VJ-nx
+start-sv
+nx-UL
+FN-nx
+FN-zl
+end-VJ
+sv-hi
+em-VJ
+start-hi
+sv-em
+end-zl
+zl-em
+hi-VJ
+FN-em
+start-VJ
+jx-FN
+zl-sv
+FN-sv
+FN-hi
+nx-end

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/data/2021/13.txt	Mon Dec 13 12:42:30 2021 -0500
@@ -0,0 +1,833 @@
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+
+fold along x=655
+fold along y=447
+fold along x=327
+fold along y=223
+fold along x=163
+fold along y=111
+fold along x=81
+fold along y=55
+fold along x=40
+fold along y=27
+fold along y=13
+fold along y=6

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/2021/days/day-11.lisp	Mon Dec 13 12:42:30 2021 -0500
@@ -0,0 +1,48 @@
+(advent:defpackage* :advent/2021/11)
+(in-package :advent/2021/11)
+
+(defun simulate (data steps &aux (result 0))
+  (destructuring-bind (rows cols) (array-dimensions data)
+    (iterate
+      (for step :from 0)
+      (for flashed-this-round = 0)
+      (for to-flash = '())
+      (when steps
+        (until (= step steps)))
+      (labels ((inc (r c)
+                 (when (array-in-bounds-p data r c)
+                   (when (= 10 (incf (aref data r c)))
+                     (push (cons r c) to-flash))))
+               (initial-phase ()
+                 (do-range ((r 0 rows)
+                            (c 0 cols))
+                   (inc r c)))
+               (flash (row col)
+                 (incf flashed-this-round)
+                 (iterate
+                   (for (r c) :within-radius 1 :origin (row col) :skip-origin t)
+                   (inc r c)))
+               (flashing-phase ()
+                 (iterate (while to-flash)
+                          (for (r . c) = (pop to-flash))
+                          (flash r c)))
+               (reset-phase ()
+                 (do-array (n data)
+                   (when (>= n 10)
+                     (setf n 0)))))
+        (initial-phase)
+        (flashing-phase)
+        (reset-phase))
+      (if steps
+        (incf result flashed-this-round) ; part 1
+        (when (= flashed-this-round (* rows cols)) ; part 2
+          (return-from simulate (1+ step))))))
+  result)
+
+(define-problem (2021 11) (stream) (1594 437)
+  (let ((data (read-2d-array stream :key #'digit-char-p)))
+    (values (simulate (alexandria:copy-array data) 100)
+            (simulate (alexandria:copy-array data) nil))))
+
+
+#; Scratch --------------------------------------------------------------------

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/2021/days/day-12.lisp	Mon Dec 13 12:42:30 2021 -0500
@@ -0,0 +1,54 @@
+(advent:defpackage* :advent/2021/12)
+(in-package :advent/2021/12)
+
+(defun edge (graph from to)
+  (push to (gethash from graph))
+  (push from (gethash to graph)))
+
+(defun parse (stream)
+  (iterate
+    (with-result graph = (make-hash-table))
+    (for line :in-stream stream :using #'read-line)
+    (for (from to) = (str:split #\- line))
+    (edge graph (intern from :advent/2021/12) (intern to :advent/2021/12))))
+
+(defun bigp (cave)
+  (upper-case-p (char (symbol-name cave) 0)))
+
+(defun restrict-small-1 (node path)
+  (member node path))
+
+(defun used-small-twice (path)
+  ;; todo do something faster than this
+  (iterate (for (a . rest) :on path)
+           (unless (bigp a)
+             (dolist (b rest)
+               (thereis (eql a b))))))
+
+(defun restrict-small-2 (node path)
+  (cond
+    ((member node '(|start| |end|)) (member node path))
+    ((used-small-twice path) (member node path))
+    (t (member node (rest (member node path))))))
+
+(defun neighbors (graph path &key restriction)
+  (iterate (for node :in (gethash (first path) graph))
+           (when (or (bigp node) (not (funcall restriction node path)))
+             (collect node))))
+
+(defun paths (graph &key restriction)
+  (recursively ((path '(|start|)))
+    (if (eql '|end| (first path))
+      1
+      (iterate (for next :in (neighbors graph path :restriction restriction))
+               (summing (recur (cons next path)))))))
+
+(define-problem (2021 12) (graph parse) (5254 149385)
+  (values (paths graph :restriction #'restrict-small-1)
+          (paths graph :restriction #'restrict-small-2)))
+
+
+
+
+#; Scratch --------------------------------------------------------------------
+

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/2021/days/day-13.lisp	Mon Dec 13 12:42:30 2021 -0500
@@ -0,0 +1,47 @@
+(advent:defpackage* :advent/2021/13)
+(in-package :advent/2021/13)
+
+(defun dot (x y) (complex x y))
+(defun x (dot) (realpart dot))
+(defun y (dot) (imagpart dot))
+
+(defun parse (lines)
+  (iterate
+    (for line :in lines)
+    (ppcre:register-groups-bind ((#'parse-integer x y)) ("(\\d+),(\\d+)" line)
+      (collect (dot x y) :into dots))
+    (ppcre:register-groups-bind (axis n) ("fold along ([xy])=(\\d+)" line)
+      (collect (cons (char axis 0) (parse-integer n)) :into folds))
+    (returning dots folds)))
+
+(defun fold% (fold dot)
+  (destructuring-bind (axis . n) fold
+    (ecase axis
+      (#\x (if (> (x dot) n)
+             (complex (- n (- (x dot) n)) (y dot))
+             dot))
+      (#\y (if (> (y dot) n)
+             (complex (x dot) (- n (- (y dot) n)))
+             dot)))))
+
+(defun fold (fold dots)
+  (map-into dots (curry #'fold% fold) dots))
+
+(defun dots-to-hash-table (dots)
+  (iterate (for dot :in dots) (collect-hash (dot #\█))))
+
+(defun part1 (dots folds &aux (dots (copy-list dots)))
+  (length (remove-duplicates (fold (first folds) dots))))
+
+(defun part2 (dots folds &aux (dots (copy-list dots)))
+  (map nil (rcurry #'fold dots) folds)
+  ;; (print-hash-table-map (dots-to-hash-table dots) :flip-y t)
+  "WELP") ; My part 2 answer contains a slur so let's not hardcode THAT test case here.
+
+(define-problem (2021 13) (lines read-lines) (682 "WELP")
+  (multiple-value-bind (dots folds) (parse lines)
+    (values (part1 dots folds)
+            (part2 dots folds))))
+
+#; Scratch --------------------------------------------------------------------
+