Initial data commit

Task/Dijkstras-algorithm/Emacs-Lisp/dijkstras-algorithm.l

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+;; Path format: (start-point end-point previous-point distance)
+(setq path-list `(
+		  (a b ,nil 7)
+		  (a c ,nil 9)
+		  (a f ,nil 14)
+		  (b c ,nil 10)
+		  (b d ,nil 15)
+		  (c d ,nil 11)
+		  (c f ,nil 2)
+		  (d e ,nil 6)
+		  (e f ,nil 9)
+		  ))
+
+(defun calculate-shortest-path ()
+  (let ((shortest-path '())
+	(head-point (nth 0 (nth 0 path-list))))
+
+    (defun combine-new-path (path1 path2)
+      (list (nth 0 path1) (nth 1 path2) (nth 0 path2)
+	    (+ (nth 3 path1) (nth 3 path2))) )
+
+    (defun find-shortest-path (start end)
+      (seq-find (lambda (item)
+		  (and (eq (nth 0 item) start) (eq (nth 1 item) end)))
+		shortest-path)
+      )
+
+    (defun add-shortest-path (item)
+      (add-to-list 'shortest-path item) )
+
+
+    (defun process-path (path)
+
+      (if (eq head-point (nth 0 path))
+	  (add-to-list 'shortest-path path)
+	(progn
+	  (dolist (spath shortest-path)
+	    (when (eq (nth 1 spath) (nth 0 path))
+	      (let* ((new-path (combine-new-path spath path))
+		     (spath-found (find-shortest-path (nth 0 new-path)
+						      (nth 1 new-path))))
+		(if spath-found
+		    (when (< (nth 3 new-path) (nth 3 spath-found))
+		      (setcdr (nthcdr 1 spath-found) (list (nth 2 new-path) (nth 3 new-path)))
+		      )
+
+		  (add-shortest-path new-path)) ) ) ) ) ) )
+
+
+    (defun find-shortest-route (start end)
+      (let ((point-list '())
+	    (end-point end)
+	    path-found)
+	(add-to-list 'point-list end)
+	(catch 'no-more-path
+	  (while 't
+	    (setq path-found (find-shortest-path start end-point))
+	    (if (or (not path-found) (not (nth 2 path-found)))
+		(throw 'no-more-path nil)
+	      (progn
+		(add-to-list 'point-list (nth 2 path-found))
+		(setq end-point (nth 2 path-found)) )
+	      )
+	    )
+	  )
+	(add-to-list 'point-list start)
+	)
+      )
+
+    (defun show-shortest-path (start end)
+      (let ((path-found (find-shortest-path start end))
+	    (route-found (find-shortest-route start end)))
+	(if path-found
+	    (progn
+	      (message "shortest distance: %s" (nth 3 path-found))
+	      (message "shortest route: %s" route-found) )
+	  (message "shortest path not found") )
+	)
+      (message "--") )
+
+    ;; Process each path
+    (dolist (path path-list)
+      (process-path path) )
+
+    (message "from %s to %s:" 'a 'e)
+    (show-shortest-path 'a 'e)
+    (message "from %s to %s:" 'a 'f)
+    (show-shortest-path 'a 'f)
+
+    )
+  )
+
+(calculate-shortest-path)