commit - fbf3f987e153a05c6fed487dfd94c2ce5677b575
commit + 7bd93562fa1827db036c3b25cfe787b809b12669
blob - /dev/null
blob + 44d2830eeef2a910fd051ff9f435f6131f2a45cf (mode 644)
--- /dev/null
+++ input/10.txt
@@ -0,0 +1,46 @@
+6543298761232134567654321234365430109789210765
+7630165450545023698743430143278121218654307876
+8781074305656712587412945056189054327610128965
+9692181212789803654307876567098769016501201234
+8543290325654908743216521098778978039432343210
+1012107812343219210127432101065432128765464569
+8703456901432101021858921098123498012346678978
+9698767876545832210961012567898567109656541066
+0543678989836943367878983456547010478765432127
+1234569834787894450123672561032123567345345698
+8705450125690765645674501870129854438936216787
+9612325678501234734983465985438763520127303456
+0549814789456789821567874376579654011298012367
+1236703210321098980432989210189503567885410198
+0145610123010123671301065123679012456956328765
+2125898016134564547219874034578654320167019954
+1034567667821078998765723410165743210298907823
+2101215454910899789054010567234894109347876910
+3432109323856789670123120198654301078456585410
+4569218012541008765434103296785212562345694321
+5678107873432210894120254589698943421034783210
+6760256976501345703091345678899874014345115432
+5801345488989856912782987010710762321236006781
+4912352397430767824653456123601051430347112390
+3983401256521956543241089234512340554398203454
+2876510342107867852130176541329429663294345965
+1089459656236238901021287430458218776187654874
+2012368789845121652012396521567309889076567876
+3001871656903030743189465432456456776985678945
+2100980347812349876676576321078944567034569432
+3231291210101656734589689234561323498123253211
+4945387667892109825678710105430212234510104500
+5876456108743276710265431016521001107601067601
+6700123219654985610176721037815410098432188932
+5217634508989414323789872348906321016501098543
+4398549607678501234567961059817892107890107676
+3210498714565430104498854367876765226981238985
+4782107123645621223421343458987014312876543214
+5693898034564789014530012121898123103987454103
+8764796543673298987645430010987035654036567812
+9855687234982187656786521027876546789145658901
+8544590127651012565497890038985589690237849878
+1234210098545671434387912147104676521056932569
+0110367653234780301275403456203465432345691410
+3223458910125691215676323569312394341210780323
+4334389871210101234981019878456787430101671410
blob - /dev/null
blob + 7a7afbfb9a4f41237e4858886b63c6724aa7a5f6 (mode 644)
--- /dev/null
+++ src/day-10.lisp
@@ -0,0 +1,52 @@
+(defpackage #:aoc/day-10
+  (:use #:cl #:aoc/utils)
+  (:export #:day-10))
+(in-package #:aoc/day-10)
+
+(defun find-trailheads (map)
+  (loop for y from 0 below (input-map-height map)
+        nconc (loop for x from 0 below (input-map-width map)
+                    for point = (cons x y)
+                    for cell = (map-cell map point)
+                    when (char= cell #\0)
+                      collect point)))
+
+(defparameter *trail-neighbours*
+  (list (cons 0 -1)
+        (cons -1 0)
+        (cons 1 0)
+        (cons 0 1)))
+
+(defun score (map trailhead)
+  (let ((map-width (input-map-width map))
+        (map-height (input-map-height map))
+        (points (make-hash-table :test #'equal))
+        (rating 0))
+    (labels ((%walk (pos)
+               (when (char= (map-cell map pos) #\9)
+                 (setf (gethash pos points) t)
+                 (incf rating)
+                 (return-from %walk nil))
+               (loop with height = (char-number (map-cell map pos))
+                     for np in (loop for nd in *trail-neighbours*
+                                     for np = (point+ pos nd)
+                                     when (point-in-bounds-p np map-width map-height)
+                                       collect np)
+                     for nc = (map-cell map np)
+                     when (and (not (char= nc #\.))
+                               (= (- (char-number nc)
+                                     height)
+                                  1))
+                       do (%walk np))))
+      (%walk trailhead)
+      (values (length (hash-table-keys points))
+              rating))))
+
+(defun day-10 (input)
+  (loop with map = (make-map input)
+        with trailheads = (find-trailheads map)
+        for trailhead in trailheads
+        for (score rating) = (multiple-value-list (score map trailhead))
+        sum score into task-1
+        sum rating into task-2
+        finally (return (values task-1 task-2))))
blob - /dev/null
blob + fc62164d7467dbd8a17a4687b3320182d78e6132 (mode 644)
--- /dev/null
+++ t/day-10.lisp
@@ -0,0 +1,64 @@
+(defpackage #:aoc-test/day-10
+  (:use #:cl #:lisp-unit2)
+  (:import-from #:aoc/day-10))
+(in-package #:aoc-test/day-10)
+
+(define-test test-day-10
+    ()
+  (assert= 2 (aoc:run-day 10 "...0...
+...1...
+...2...
+6543456
+7.....7
+8.....8
+9.....9"))
+  (assert= 4 (aoc:run-day 10 "..90..9
+...1.98
+...2..7
+6543456
+765.987
+876....
+987...."))
+  (assert= 3 (aoc:run-day 10 "10..9..
+2...8..
+3...7..
+4567654
+...8..3
+...9..2
+.....01"))
+  (assert= 36 (aoc:run-day 10 "89010123
+78121874
+87430965
+96549874
+45678903
+32019012
+01329801
+10456732"))
+  (assert= 3 (nth-value 1 (aoc:run-day 10 ".....0.
+..4321.
+..5..2.
+..6543.
+..7..4.
+..8765.
+..9....")))
+  (assert= 13 (nth-value 1 (aoc:run-day 10 "..90..9
+...1.98
+...2..7
+6543456
+765.987
+876....
+987....")))
+  (assert= 227 (nth-value 1 (aoc:run-day 10 "012345
+123456
+234567
+345678
+4.6789
+56789.")))
+  (assert= 81 (nth-value 1 (aoc:run-day 10 "89010123
+78121874
+87430965
+96549874
+45678903
+32019012
+01329801
+10456732"))))