;;; Michael Wollowski
;;; A5

(define (rl) (load "5.ss"))

(define free-vars
  (case-lambda
   [(exp) (free-vars exp '() '())]
   [(exp free bound)
    (cond [(null? exp) free]
	  [(symbol? exp)
	   (if (memq exp bound)
	       free
	       (merge exp free))]
	  [(eq? (car exp) 'lambda)
	   (free-vars (cddr exp) free (merge (cadr exp) bound))]
	  [(null? (cdr exp)) (free-vars (car exp) free bound)]
	  [else (merge (free-vars (car exp) free bound)
		       (free-vars (cadr exp) free bound))])]))


(define merge
  (lambda (x y)
    (cond [(null? x) y]
	  [(symbol? x) (if (memq x y)
			   y
			   (cons x y))]
	  [else (merge (car x) (merge (cdr x) y))])))


(define bound-vars
  (case-lambda
   [(exp) (bound-vars exp '())]
   [(exp bound)
    (cond [(null? exp) ()]
	  [(symbol? exp)
	   (if (memq exp bound)
	       (list exp)
	       ())]
	  [(eq? (car exp) 'lambda)
	   (bound-vars (cddr exp) (append (cadr exp) bound))]
	  [(null? (cdr exp)) (bound-vars (car exp) bound)]
	  [else (append (bound-vars (car exp) bound)
			(bound-vars (cadr exp) bound))])]))

	  



(define gr '((a (b c)) (b (a)) (c (a)) (d ())))

(define connected?
  (lambda (g)
    (cond [(null? g)]
	  [(and (null? (cdr g))
		(null? (cdar g)))]
	  [else (let* ([nodes (map car g)]
		       [startEndPoints (make_start_end_points nodes)])
		  (paths? startEndPoints g))])))

(define make_start_end_points
  (lambda (l)
    (if (null? (cdr l))
	()
	(append (map (lambda (x) (list (car l) x)) (cdr l))
		(make_start_end_points (cdr l))))))


(define paths?
  (lambda (SEPoints g)
    (if (null? SEPoints)
	#t
	(and (path? (cadar SEPoints) g (caar SEPoints))
	     (paths? (cdr SEPoints) g)))))

		
;(define path?
;  (lambda (endPoint g openqueue closedqueue )
;    (cond [(null? queue) #f]
;	  [(eq? (car queue) endPoint) #t]
;	  [else (path? endPoint g (append (cdr queue) ;;; remove duplicates from open and closed


;(get (car queue) g)))])))

(define get
  (lambda (e g)
    (cond [(null? g) ()]
	  [(eq? e (caar g)) (cadar g)]
	  [else (get e (cdr g))])))	

(define remove-duplicates
  (lambda (l1 l2)
    (if (null? l1)
	l2
	(remove-duplicates (cdr l1) (remq (car l1) l2)))))