5 files changed, 186 insertions(+), 3 deletions(-)

M 2022/aoc-2022.asd
A 2022/day12.lisp
A 2022/inputs/12
M utils/grid.lisp
M utils/packages.lisp

@@ 10,4 10,5 @@
                (:file "day08")
                (:file "day09")
                (:file "day10")
-               (:file "day11")))
+               (:file "day11")
+               (:file "day12")))

@@ 0,0 1,85 @@
+(defpackage :aoc-2022-day12
+  (:use :cl))
+(in-package :aoc-2022-day12)
+
+(defparameter *test-input* "Sabqponm
+abcryxxl
+accszExk
+acctuvwj
+abdefghi")
+
+(defun read-input (input)
+  (let* ((g (aoc:dense-grid-from-string input))
+         (start (aoc:grid-find #\S g :test #'char=))
+         (end (aoc:grid-find #\E g :test #'char=)))
+    (setf (aoc:grid-xy g (car start) (cdr start)) #\a)
+    (setf (aoc:grid-xy g (car end) (cdr end)) #\z)
+    (list :grid g
+          :start start
+          :end end)))
+
+(defun part1 (data)
+  (let* ((g (getf data :grid))
+         (start (getf data :start))
+         (end (getf data :end))
+         (bb (aoc:grid-bounding-box g))
+         (width (1+ (nth 2 bb)))
+         (height (1+ (nth 3 bb)))
+         (moves (aoc:make-dense-grid width height)))
+    (setf (aoc:grid-xy moves (car end) (cdr end)) 0)
+    (loop with next = (list end)
+          while next
+          while (null (aoc:grid-xy moves (car start) (cdr start)))
+          for m from 1
+          do (loop with changed = nil
+                   for (px . py) in next
+                   for ph = (- (char-code (aoc:grid-xy g px py))
+                               (char-code #\a))
+                   do (loop for (nx . ny) in (aoc:grid-neighbors g px py)
+                            for nh = (- (char-code (aoc:grid-xy g nx ny))
+                                        (char-code #\a))
+                            when (and (null (aoc:grid-xy moves nx ny))
+                                      (>= nh (1- ph)))
+                              do (setf (aoc:grid-xy moves nx ny) m)
+                                 (pushnew (cons nx ny) changed :test #'equal))
+                   finally (setf next changed)))
+    (aoc:grid-xy moves (car start) (cdr start))))
+
+(defun part2 (data)
+  (let* ((g (getf data :grid))
+         (end (getf data :end))
+         (bb (aoc:grid-bounding-box g))
+         (width (1+ (nth 2 bb)))
+         (height (1+ (nth 3 bb)))
+         (moves (aoc:make-dense-grid width height)))
+    (setf (aoc:grid-xy moves (car end) (cdr end)) 0)
+    (block outer
+      (loop with next = (list end)
+            while next
+            for m from 1
+            do (loop with changed = nil
+                     for (px . py) in next
+                     for ph = (- (char-code (aoc:grid-xy g px py))
+                                 (char-code #\a))
+                     do (loop for (nx . ny) in (aoc:grid-neighbors g px py)
+                              for nv = (aoc:grid-xy g nx ny)
+                              for nh = (- (char-code nv)
+                                          (char-code #\a))
+                              when (and (null (aoc:grid-xy moves nx ny))
+                                        (>= nh (1- ph)))
+                                do (setf (aoc:grid-xy moves nx ny) m)
+                                   (pushnew (cons nx ny) changed :test #'equal)
+                                   (when (char= nv #\a) (return-from outer m)))
+                     finally (setf next changed))))))
+
+
+(aoc:defpuzzle day12
+  :test-data (list *test-input*)
+  :test-results-part1 '(31)
+  :test-results-part2 '(29)
+  :read-input #'read-input
+  :part1 #'part1
+  :part2 #'part2)
+
+;; (day12 :test)
+;; (day12)

@@ 0,0 1,41 @@
+abccccccccccccccccccaaaaaaaaacccccccccccccccccccccccccccccccccccccaaaa
+abcccccccccccccccaaaaaaaaaaacccccccccccccccccccccccccccccccccccccaaaaa
+abcaaccaacccccccccaaaaaaaaaacccccccccccccccccccccaaacccccccccccccaaaaa
+abcaaaaaaccccccccaaaaaaaaaaaaacccccccccccccccccccaacccccccccccccaaaaaa
+abcaaaaaacccaaacccccaaaaaaaaaaaccccccccccccccccccaaaccccccccccccccccaa
+abaaaaaaacccaaaaccccaaaaaacaaaacccccccccccaaaacjjjacccccccccccccccccca
+abaaaaaaaaccaaaaccccaaaaaaccccccaccccccccccaajjjjjkkcccccccccccccccccc
+abaaaaaaaaccaaacccccccaaaccccccaaccccccccccajjjjjjkkkaaacccaaaccaccccc
+abccaaacccccccccccccccaaccccaaaaaaaacccccccjjjjoookkkkaacccaaaaaaccccc
+abcccaacccccccccccccccccccccaaaaaaaaccccccjjjjoooookkkkcccccaaaaaccccc
+abcccccccaacccccccccccccccccccaaaacccccccijjjoooooookkkkccaaaaaaaccccc
+abccaaccaaaccccccccccccccccccaaaaacccccciijjooouuuoppkkkkkaaaaaaaacccc
+abccaaaaaaaccccccccccaaaaacccaacaaaccciiiiiooouuuuupppkkklllaaaaaacccc
+abccaaaaaacccccccccccaaaaacccacccaaciiiiiiqooouuuuuupppkllllllacaccccc
+abcccaaaaaaaacccccccaaaaaaccccaacaiiiiiqqqqoouuuxuuupppppplllllccccccc
+abccaaaaaaaaaccaaaccaaaaaaccccaaaaiiiiqqqqqqttuxxxuuuppppppplllccccccc
+abccaaaaaaaacccaaaaaaaaaaacccaaaahiiiqqqttttttuxxxxuuuvvpppplllccccccc
+abcaaaaaaacccaaaaaaaaaaacccccaaaahhhqqqqtttttttxxxxuuvvvvvqqlllccccccc
+abcccccaaaccaaaaaaaaaccccccccacaahhhqqqttttxxxxxxxyyyyyvvvqqlllccccccc
+abcccccaaaccaaaaaaaacccccccccccaahhhqqqtttxxxxxxxyyyyyyvvqqqlllccccccc
+SbcccccccccccaaaaaaaaaccccccccccchhhqqqtttxxxxEzzzyyyyvvvqqqmmlccccccc
+abcccccccccccaaaaaaaacccaacccccccchhhppptttxxxxyyyyyvvvvqqqmmmcccccccc
+abccccccccccaaaaaaaaaaccaacccccccchhhpppptttsxxyyyyyvvvqqqmmmccccccccc
+abcaacccccccaaaaaaacaaaaaaccccccccchhhppppsswwyyyyyyyvvqqmmmmccccccccc
+abaaaacccccccaccaaaccaaaaaaacccccccchhhpppsswwyywwyyyvvqqmmmddcccccccc
+abaaaaccccccccccaaaccaaaaaaacccccccchhhpppsswwwwwwwwwvvqqqmmdddccccccc
+abaaaacccccccccaaaccaaaaaaccccccccccgggpppsswwwwrrwwwwvrqqmmdddccccccc
+abccccccaaaaaccaaaacaaaaaaccccccaacccggpppssswwsrrrwwwvrrqmmdddacccccc
+abccccccaaaaaccaaaacccccaaccccaaaaaacggpppssssssrrrrrrrrrnmmdddaaccccc
+abcccccaaaaaaccaaaccccccccccccaaaaaacggppossssssoorrrrrrrnnmdddacccccc
+abcccccaaaaaaccccccccaaaaccccccaaaaacgggoooossoooonnnrrnnnnmddaaaacccc
+abccccccaaaaaccccccccaaaacccccaaaaaccgggoooooooooonnnnnnnnndddaaaacccc
+abccccccaaaccccccccccaaaacccccaaaaacccgggoooooooffennnnnnnedddaaaacccc
+abcccccccccccccccccccaaacccccccaacccccggggffffffffeeeeeeeeeedaaacccccc
+abccccccccccccccccccaaacccccaccaaccccccggfffffffffeeeeeeeeeecaaacccccc
+abccccccccccccccccccaaaacccaaaaaaaaaccccfffffffaaaaaeeeeeecccccccccccc
+abccccccccaacaaccccaaaaaacaaaaaaaaaaccccccccccaaaccaaaaccccccccccccccc
+abccccccccaaaaacccaaaaaaaaaaacaaaaccccccccccccaaaccccaaccccccccccaaaca
+abcccccccaaaaaccccaaaaaaaaaaacaaaaacccccccccccaaaccccccccccccccccaaaaa
+abcccccccaaaaaacccaaaaaaaaaacaaaaaacccccccccccaaccccccccccccccccccaaaa
+abcccccccccaaaaccaaaaaaaaaaaaaaccaaccccccccccccccccccccccccccccccaaaaa

@@ 61,7 61,8 @@
            (width (- end start -1)))
       (make-array width
                   :displaced-to data
-                  :displaced-index-offset (array-row-major-index data y start)))))
+                  :displaced-index-offset (array-row-major-index data y start)
+                  :element-type (array-element-type data)))))
 
 (defgeneric grid-column (grid x &key up-from down-from)
   (:documentation "Return a column from the grid.")


@@ 101,7 102,7 @@
       (list 0 0 (1- width) (1- height)))))
 
 (defgeneric grid-size (grid)
-  (:documentation "Reutnr the number of set points in the grid.")
+  (:documentation "Return the number of set points in the grid.")
   (:method ((g sparse-grid))
     (hash-table-count (sparse-grid-data g))))
 


@@ 118,3 119,54 @@
                             (otherwise grid-value))
               do (format out "~a~a" value h-space)
               finally (format out "~%"))))))
+
+(defun dense-grid-from-string (s)
+  "Build a dense grid from a string."
+  (let ((lines (str:lines s)))
+    (loop with g = (make-dense-grid (length (car lines)) (length lines))
+          for line in lines
+          for y from 0
+          do (loop for char across line
+                   for x from 0
+                   do (setf (grid-xy g x y) char))
+          finally (return g))))
+
+(defgeneric grid-find-if (predicate grid)
+  (:documentation "Return the coords of the first value in GRID that satisfies PREDICATE.")
+  (:method (predicate (g sparse-grid))
+    (loop for coords being the hash-keys in (sparse-grid-data g) using (hash-value value)
+          when (funcall predicate value) do
+            (return (cons (realpart value)
+                          (imagpart value)))
+          finally (return nil)))
+  (:method (predicate (g dense-grid))
+    (alexandria:when-let* ((data (dense-grid-data g))
+                           (idx (position-if predicate
+                                             (make-array (array-total-size data)
+                                                         :displaced-to data
+                                                         :element-type (array-element-type data)))))
+      (multiple-value-bind (y x) (floor idx (array-dimension data 1))
+        (cons x y)))))
+
+(defun grid-find (item grid &key (test #'eql))
+  "Return the coords of the first instance of ITEM in GRID."
+  (grid-find-if (lambda (it) (funcall test it item)) grid))
+
+(defgeneric grid-neighbors (grid x y)
+  (:documentation "Return the coords of all neighbors.")
+  (:method ((g sparse-grid) x y)
+    (list (cons (1+ x) y)
+          (cons (1- x) y)
+          (cons x (1+ y))
+          (cons x (1- y))))
+  (:method ((g dense-grid) x y)
+    (loop with dim = (array-dimensions (dense-grid-data g))
+          for (xx . yy) in (list (cons (1+ x) y)
+                                 (cons (1- x) y)
+                                 (cons x (1+ y))
+                                 (cons x (1- y)))
+          when (and (>= xx 0)
+                    (>= yy 0)
+                    (< xx (cadr dim))
+                    (< yy (car dim)))
+            collect (cons xx yy))))

@@ 24,6 24,10 @@
    #:grid-bounding-box
    #:grid-size
    #:grid-print
+   #:dense-grid-from-string
+   #:grid-find-if
+   #:grid-find
+   #:grid-neighbors
 
    ;; sequence
    #:chunks