day 22 part 1

22-reactor-reboot/code.scm

@@ -0,0 +1,74 @@
+(load "../common.scm")
+
+(define (read-cuboid-operation file)
+  (let* [(on/off (if (symbol=? (get-datum file) 'on) 1 0))
+	 (x-start (begin (get-string-n file 3) (get-number file))) ; skipping " x="
+	 (x-end (begin (get-string-n file 1) (get-number file)))   ; skipping dot
+	 (y-start (begin (get-string-n file 2) (get-number file))) ; skipping "y="
+	 (y-end (begin (get-string-n file 1) (get-number file)))   ; skipping dot
+	 (z-start (begin (get-string-n file 2) (get-number file))) ; skipping "z="
+	 (z-end (begin (get-string-n file 1) (get-number file)))]  ; skipping dot
+    (list on/off x-start x-end y-start y-end z-start z-end)))
+
+(define (load-cuboid-ops filename)
+  (call-with-input-file
+    filename
+    (lambda (file)
+      (let loop [(ops '())]
+	(if (eof-object? (peek-char file))
+	  (reverse ops)
+	  (loop (cons (read-cuboid-operation file) ops)))))))
+
+(define (make-3d-vector x-size y-size z-size init)
+  (let x-loop [(x 0) (planes '())]
+    (if (= x x-size)
+      (reverse-list->vector planes)
+      (x-loop (+ x 1)
+	      (cons
+		(let y-loop [(y 0) (lines '())]
+		  (if (= y y-size)
+		    (reverse-list->vector lines)
+		    (y-loop (+ y 1) (cons (make-vector z-size init) lines))))
+		planes)))))
+
+; set 3D volume to given value
+; end ranges are inclusive!
+(define (vector-3d-set! 3d-vector value x-start x-end y-start y-end z-start z-end)
+  (let [(width (- (vector-length (vector-ref (vector-ref 3d-vector 0) 0)) 1))
+	(height (- (vector-length (vector-ref 3d-vector 0)) 1))
+	(depth (- (vector-length 3d-vector) 1))]
+    (let x-loop [(x (max x-start 0))]
+      (unless (> x (min x-end width))
+	(let y-loop [(y (max y-start 0))]
+	(unless (> y (min y-end height))
+	  (let z-loop [(z (max z-start 0))]
+	  (unless (> z (min z-end depth))
+	    (vector-set! (vector-ref (vector-ref 3d-vector x) y) z value)
+	    (z-loop (+ z 1))))
+	(y-loop (+ y 1))))
+    (x-loop (+ x 1))))))
+
+(define (vector-3d-sum 3d-vector)
+  (vector-fold
+    (lambda (i a v)
+      (+ a (vector-fold
+	     (lambda (i a v)
+	       (+ a (vector-fold
+		      (lambda (i a v) (+ a v))
+		      0 v)))
+	     0 v)))
+    0 3d-vector))
+
+(let [(operations (load-cuboid-ops "input"))
+      (grid (make-3d-vector 101 101 101 0))]
+  (let operate [(op operations)]
+    (unless (null? op)
+      (apply vector-3d-set! grid
+	     (cons (caar op) 
+		   ; offset x/y/z ranges from -50..50 to 0..101 to fit in 3d-vector
+		   (map (lambda (x) (+ x 50)) (cdar op))))
+      (operate (cdr op))))
+  (printf "part 1:~% Cubes powered after initialization procedure: ~a~%"
+	  (vector-3d-sum grid)))
+
+;; do step 2 using a sparse voxel octree ?