day 8 cleaning up code

day8-tree-heights.lisp

@@ -227,7 +227,7 @@
             (incf running-sum 1))))
     running-sum))
 
-;;; wow, 1835 was the right answer. urrgh
+;;; wow, 1845 was the right answer. urrgh
 ;;; now to the second part
 ;; and that's totally different thing now.
 ;; i guess i could use my "col-line" to get coords to check from the tree
@@ -367,6 +367,141 @@
         (if (> cur-tree-score cur-max)
             (setq cur-max cur-tree-score)))))
   cur-max)
+;; 230112 is the correct answer
 
 ;; wow. i got an aswer 8
 ;; now try to recalculate this horrible thing with actual input.
+
+;;; let's CLEAN UP THE CODE, at least set it all together
+;;; PART 1: Count visible trees
+
+(defparameter *file-name* "day8-input.txt")
+(progn
+  (defparameter *trees-2d-vector*
+    (let ((rows-accumulation ()))
+      (with-open-file (in *file-name*)
+        (loop
+          for line = (read-line in nil nil)
+          while line
+          do (push
+              (coerce (mapcar #'parse-integer (cl-ppcre:split "" line)) 'vector)
+              rows-accumulation)
+          )
+        (coerce (reverse rows-accumulation) 'vector))))
+  (defparameter *trees-rownum* (length *trees-2d-vector*))
+  (defparameter *trees-colnum* (length (aref *trees-2d-vector* 0))))
+
+;; generate Visibility matrix for trees
+(defparameter *tree-vis-matr*
+  (let* ((rows-count (length *trees-2d-vector*))
+         (cols-count (length (aref *trees-2d-vector* 0)))
+         (visibility-matrix (make-array (list rows-count cols-count) :initial-element nil)))
+
+    (iterate:iter (for rownum from 0 to (1- rows-count)) ; trying iter to avoid nested LOOP
+      (iterate:iter (for colnum from 0 to (1- cols-count))
+        (if (or (= rownum 0)
+                (= rownum (1- rows-count))
+                (= colnum 0)
+                (= colnum (1- cols-count)))
+            (setf (aref visibility-matrix rownum colnum) 'T))))
+    visibility-matrix))
+
+;; get list of coordinates towards DIRECTION, starting from startRow & startCol
+;; for generalizing LOOP'ing into different directions
+(defun gen-line-coords (startRow startCol rowNum colNum direction)
+  (flet ((row-col-valid (row col)
+           (and (>= row 0) (>= col 0) (< row rowNum) (< col colNum)))
+         (nextPoint (row col)
+           (case direction
+             ('LEFT (list row (1- col)))
+             ('RIGHT (list row (1+ col)))
+             ('UP (list (1- row) col))
+             ('DOWN (list (1+ row) col)))))
+    (let ((coords-collected ()))
+      (do
+       ((coords (list startRow startCol) (apply #'nextpoint coords)))
+       ((not (apply #'row-col-valid coords)) (reverse coords-collected))
+       (push coords coords-collected)))))
+
+
+(progn
+  ;; this is with unfortunate amount of manual tinkering
+  (defparameter *trees-right-line-coords*
+    (loop
+      for startRow from 0 below *trees-rownum*
+      collect (gen-line-coords startRow 0 *trees-rownum* *trees-colnum* 'right)))
+
+  (defparameter *trees-left-line-coords*
+    (loop
+      for startRow from 0 below *trees-rownum*
+      collect (gen-line-coords startRow (1- *trees-colnum*) *trees-rownum* *trees-colnum* 'left)))
+
+  (defparameter *trees-right-down-coords*
+    (loop
+      for startCol from 0 below *trees-colnum*
+      collect (gen-line-coords 0 startCol *trees-rownum* *trees-colnum* 'down)))
+
+  (defparameter *trees-right-up-coords*
+    (loop
+      for startCol from 0 below *trees-colnum*
+      collect (gen-line-coords (1- *trees-rownum*) startCol *trees-rownum* *trees-colnum* 'up)))
+
+  (defparameter *trees-all-line-coords*
+    (concatenate 'list
+                 *trees-right-line-coords*
+                 *trees-left-line-coords*
+                 *trees-right-down-coords*
+                 *trees-right-up-coords*))
+
+;;; iterate over all col-lines
+  (loop
+    for coord-line in *trees-all-line-coords*
+    do (let ((biggest-tree-so-far -1))
+         (loop
+           for coords in coord-line
+           do (let* ((rownum (first coords))
+                     (colnum (second coords))
+                     (row (aref *trees-2d-vector* rownum))
+                     (tree-size (aref row colnum)))
+                (if (< biggest-tree-so-far tree-size)
+                    (progn (setq biggest-tree-so-far tree-size)
+                           (setf (aref *tree-vis-matr* rownum colnum) 't)))))))
+
+  *tree-vis-matr*
+
+  ;; counting amount of 'T in the visibility matrix
+  (let ((running-sum 0))
+    (iterate:iter (for rownum from 0 to (1- *trees-rownum*))
+      (iterate:iter (for colnum from 0 to (1- *trees-colnum*))
+        (if (aref *tree-vis-matr* rownum colnum)
+            (incf running-sum 1))))
+    running-sum))
+
+
+;;; PART 2. find tree with highest view-score
+;; from list of tree-heights take trees that lover than current, until first tree of same height or higher
+(defun my-get-prefix (trees-heights self-height)
+  (let ((self self-height)
+        (found-self nil))
+    (loop for elt in trees-heights
+          while (not found-self) collect elt
+          if (>= elt self) do (setq found-self 't))))
+
+;; use same trees 2d array. O(n^2) - for each tree construct lines into 4 directions,
+;; get prefix of these lines for trees that of not exceeding height, calculate score
+;; instead of CUR-MAX could possibly use MAXIMIZING of LOOP, or something
+(let ((cur-max -1))
+  (iterate:iter (for row from 1 to (1- *trees-rownum*))
+    (iterate:iter (for col from 1 to (1- *trees-colnum*))
+      (let* ((cur-tree-height (tree-size-by-coords (list row col)))
+             (cur-tree-lines (get-tree-direction-cols (list row col)))
+             (cur-tree-lines-tree-heights
+               (mapcar (lambda (coord-line)
+                         (mapcar #'tree-size-by-coords coord-line)) cur-tree-lines))
+             (cur-tree-visibilities
+               (mapcar (lambda (height-list)
+                         (length (my-get-prefix height-list cur-tree-height))) cur-tree-lines-tree-heights))
+             (cur-tree-score (apply #'* cur-tree-visibilities)))
+        (if (> cur-tree-score cur-max)
+            (setq cur-max cur-tree-score)))))
+  cur-max)