aoc 2025 - still need to 7

Forgot to push these all onto the cloud lol

2025/puzzle-4.lisp

@@ -0,0 +1,75 @@
+(load "util.lisp")
+
+(defpackage "aoc:4"
+  (:use :cl "aoc-util"))
+
+(in-package "aoc:4")
+
+(fn valid-cell-coord (graph x y) (=> (list fixnum fixnum) boolean)
+  (and (>= x 0) (< x (length graph))
+       (>= y 0) (< y (length (car graph)))))
+
+(fn get-cell (graph x y) (=> (list fixnum fixnum) (or null character))
+  (if (valid-cell-coord graph x y)
+      (->> graph (nth x) (nth y))
+      nil))
+
+(fn adjacent-cell-coords (graph x y) (=> (list fixnum fixnum) cons)
+  (loop
+    for x_ from (1- x) to (1+ x)
+    nconc
+    (loop
+      for y_ from (1- y) to (1+ y)
+      for cell = (get-cell graph x_ y_)
+      if cell
+        collect (list x_ y_ cell))))
+
+(fn get-rolls-with-adjacent-rolls (graph) (=> list cons)
+  (loop
+    for x from 0
+    for row in graph
+    nconc
+    (loop
+      for y from 0
+      for cell in row
+      if (char= cell #\@)
+        collect
+        (->> (adjacent-cell-coords graph x y)
+             (remove-if-not ($>> (nth 2) (char= #\@)))
+             length
+             (list x y)))))
+
+
+(fn get-good-rolls (graph) (=> list list)
+  (->> graph
+       get-rolls-with-adjacent-rolls
+       (remove-if ($>> (nth 2) (< 4)))))
+
+(fn round-1 (graph) (=> list fixnum)
+  (->> graph
+       get-good-rolls
+       length))
+
+(fn remove-cells (graph cells) (=> (list list) list)
+  (loop for (x y) in cells
+        do (setf (->> graph (nth x) (nth y)) #\.))
+  graph)
+
+(fn round-2 (graph) (=> list fixnum)
+  (loop
+    for good-rolls = (get-good-rolls graph)
+    while (/= (length good-rolls) 0)
+    sum (length good-rolls)
+    do (->> good-rolls
+            (mapcar ($<> (subseq 0 2)))
+            (remove-cells graph)
+            (setf graph))))
+
+(let ((input (->> (uiop:read-file-lines "4-input")
+                  (mapcar #'(lambda (x) (coerce x 'list))))))
+  (->> input
+       round-1
+       (format t "Round 1: ~a~%"))
+  (->> input
+       round-2
+       (format t "Round 2: ~a~%")))