数据结构(scheme) -- 抽象数据类型(ADT) -- 图

; ==================================================================================; 图，Graph; 无向图; ((0 1 2 4);  (1 0 2);  (2 0 1 3);  (3 2 4);  (4 1 3))(define g (graph))(graph-vertex-add g 0)                      ; 添加顶点(graph-edges-add g (cons 0 1))              ; 添加边(graph-vertex-remove g 0)                   ; 删除顶点(graph-edges-remove g (cons 0 1))           ; 删除边(graph-traverse g (lambda (i) (printf "v = ~d\n" i)))  ; 深度优先遍历图(graph-vertex g)                            ; 获取图的顶点列表(graph-edges g 0)                           ; 获取图中与顶点0相连的顶点列表(graph-connected? g 1 3)                    ; 判断两顶点是否连通; =====================================================================================(define graph list)(define (graph-vertex g) (map car g))(define (graph-edges g v)  (if (null? g)      '()      (if (= v (car (car g)))          (cdr (car g))          (graph-edges (cdr g) v))))(define-syntax graph-vertex-add   (syntax-rules ()    ((_ g v)     (set! g (if (null? g)                 (list (cons v '()))                 (append g (list (cons v '()))))))))(define (graph-edges-add g p)  (if (null? g)      #f      (if (= (car p) (car (car g)))          (begin            (set-cdr! (car g) (append (cdr (car g)) (list (cdr p))))            #t)          (graph-edges-add (cdr g) p))))(define (zmap f ls)  (if (not (null? ls))      (begin (f (car ls))        (zmap f (cdr ls)))))(define-syntax graph-vertex-remove  (syntax-rules ()    ((_ g v)     (if (not (null? g))         (begin            (set! g (filter (lambda (p) (not (= v (car p)))) g))           (zmap (lambda (p)                    (set-cdr! p (filter (lambda (i) (not (= v i))) (cdr p))))                 g))))))(define (graph-edges-remove g e)  (zmap (lambda (p)          (set-cdr! p (filter                         (lambda (i)                          (not (or                                 (and (= (car p) (car e))                                      (= i (cdr e)))                                 (and (= (car p) (cdr e))                                      (= i (car e))))))                        (cdr p))))        g))(define (graph-traverse g f)  (define (graph-node g i)    (if (= i (car (car g)))        (car g)        (graph-node (cdr g) i)))  (define (dfs p)    (set-car! (cdr p) #t)    (f (car p))    (zmap (lambda (i)            (let ((q (graph-node g i)))              (if (not (car (cdr q)))                  (dfs q))))           (cdr (cdr p))))  (zmap (lambda (p) (set-cdr! p (cons #f (cdr p)))) g)  (zmap (lambda (p)          (if (not (car (cdr p)))              (dfs p)))        g)  (zmap (lambda (p) (set-cdr! p (cdr (cdr p)))) g))    (define (graph-connected? g v1 v2)  (define res #f)  (define (graph-node g i)    (if (= i (car (car g)))        (car g)        (graph-node (cdr g) i)))  (define (dfs p)    (set-car! (cdr p) #t)    (if (= v2 (car p))        (set! res #t)        (zmap (lambda (i)                (let ((q (graph-node g i)))                  (if (not (car (cdr q)))                      (dfs q))))               (cdr (cdr p)))))    (zmap (lambda (p) (set-cdr! p (cons #f (cdr p)))) g)  (dfs (graph-node g v1))  (zmap (lambda (p) (set-cdr! p (cdr (cdr p)))) g)  res)