Add fewest-vertices-path.

graph.rkt

@@ -32,7 +32,7 @@
            undirected-graph directed-graph
            matrix-graph?
 
-           bfs
+           bfs fewest-vertices-path
 
            graphviz)
 
@@ -114,6 +114,8 @@
   ;; 4.1 Breadth-first Search
   (define (bfs g source)
     (g:bfs (gg g) source))
+  (define (fewest-vertices-path G source target)
+    (g:fewest-vertices-path (gg G) source target))
 
   ;; 10 Graphviz
   (define (graphviz g #:output [output #f] #:colors [colors #f])
@@ -166,6 +168,7 @@
   ;; 4.1 Breadth-first Search
   [bfs (-> Graph Any (Values (Mutable-HashTable Any Number)
                              (Mutable-HashTable Any Any)))]
+  [fewest-vertices-path (-> Graph Any Any (U (Listof Any) False))]
 
   ;; 10 Graphviz
   [graphviz (->* (Graph)
@@ -246,7 +249,9 @@
     ;; 4.1 Breadth-first Search
     (define-values (bfs-lens bfs-tree) (bfs (directed-graph '((a b) (b c))) 'a))
     (check-equal? (hash->ordered-list bfs-lens) '((a . 0) (b . 1) (c . 2)))
-    (check-equal? (hash->ordered-list bfs-tree) '((a . #f) (b . a) (c . b))))
+    (check-equal? (hash->ordered-list bfs-tree) '((a . #f) (b . a) (c . b)))
+    (check-equal? (fewest-vertices-path (directed-graph '((a b) (b c) (c d))) 'a 'd)
+                  '(a b c d)))
 
   (test-case "10 Graphviz"
     (define g (directed-graph '((a b) (b c))))