feat(tazjin/aoc2023): day 1 solution r/7105

String splits all the way!

Change-Id: I7e7f64fb082ee2e04d895f3b7e52210610d06d39
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10184
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
Autosubmit: tazjin <tazjin@tvl.su>

1 files changed, 64 insertions, 0 deletions

diff --git a/users/tazjin/aoc2023/day2.el b/users/tazjin/aoc2023/day2.el
new file mode 100644
index 000000000000..9374d7862c64
--- /dev/null
+++ b/users/tazjin/aoc2023/day2.el
@@ -0,0 +1,64 @@
+(require 'dash)
+(require 's)
+(require 'f)
+
+(defvar aoc23-day2-example
+
+  "Game 1: 3 blue, 4 red; 1 red, 2 green, 6 blue; 2 green
+Game 2: 1 blue, 2 green; 3 green, 4 blue, 1 red; 1 green, 1 blue
+Game 3: 8 green, 6 blue, 20 red; 5 blue, 4 red, 13 green; 5 green, 1 red
+Game 4: 1 green, 3 red, 6 blue; 3 green, 6 red; 3 green, 15 blue, 14 red
+Game 5: 6 red, 1 blue, 3 green; 2 blue, 1 red, 2 green")
+
+;; part 1
+
+(cl-defstruct aoc23d2-set red green blue)
+
+(defun aoc23d2-parse-set (input)
+  (let ((set (make-aoc23d2-set :red 0 :green 0 :blue 0))
+        (colours (-map #'s-trim (s-split "," input))))
+    (cl-loop for colour in colours
+             do (pcase (s-split " " colour t)
+                  (`(,num "red") (setf (aoc23d2-set-red set) (string-to-number num)))
+                  (`(,num "green") (setf (aoc23d2-set-green set) (string-to-number num)))
+                  (`(,num "blue") (setf (aoc23d2-set-blue set) (string-to-number num)))))
+    set))
+
+(cl-defstruct aoc23d2-game id sets)
+
+(defun aoc23d2-parse-game (input)
+  (pcase-let* ((`(,id-str ,sets-str) (s-split-up-to ":" input 1 t))
+               (game-id (string-to-number (s-chop-left (length "Game ") id-str)))
+               (sets (-map #'aoc23d2-parse-set (s-split ";" sets-str t))))
+    (make-aoc23d2-game :id game-id :sets sets)))
+
+(defun aoc23d2-game-possible-p (game r g b)
+  (cl-every (lambda (set)
+              (and (<= (aoc23d2-set-red set) r)
+                   (<= (aoc23d2-set-green set) g)
+                   (<= (aoc23d2-set-blue set) b)))
+            (aoc23d2-game-sets game)))
+
+(let ((input (f-read "~/Downloads/input.txt")))
+  (-sum
+   (-map #'aoc23d2-game-id
+         (-filter (lambda (g) (aoc23d2-game-possible-p g 12 13 14))
+                  (-map #'aoc23d2-parse-game (s-lines (s-trim input)))))))
+
+;; part 2
+
+(defun aoc23d2-game-min-cubes-power (game)
+  (let ((r 0)
+        (g 0)
+        (b 0))
+    (-each (aoc23d2-game-sets game)
+      (lambda (set)
+        (setq r (max r (aoc23d2-set-red set)))
+        (setq g (max g (aoc23d2-set-green set)))
+        (setq b (max b (aoc23d2-set-blue set)))))
+    (* (max 1 r) (max 1 g) (max 1 b))))
+
+(let ((input (f-read "~/Downloads/input.txt")))
+  (-sum
+   (-map #'aoc23d2-game-min-cubes-power
+         (-map #'aoc23d2-parse-game (s-lines (s-trim input))))))