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POScheme Depth-first search of a graph function
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copied!<p>This is a homework question,I'm trying to do a Depth-first search function in Scheme,Here's the code I've written so far: </p> <pre><code>(define explore (λ(node visited) (let* ([neighbors (force (cdr node))] [next (nextNode visited neighbors)] [is-visited (member? node visited)]) (cond ;if I have no unvisited neighbours print current node and go up one level [(equal? next #f) (begin (display (car node)) (display " "))] ;if current node is not visited and I have unvisited neighbors ;print current node,mark as visited and visit it's neighbors [(and (equal? is-visited #f) (not (equal? next #f))) (begin (display (car node)) (display " ") (explore next (cons node visited)))]) ;go and visit the next neighbor (if (not (equal? (nextNode (cons next visited) neighbors) #f )) (explore (nextNode (cons next visited) neighbors) (cons node visited)))))) </code></pre> <p>'node' is the current node<br> 'visited' is a list in witch I keep track of the nodes I visited<br> 'nextNode' is a function that returns the first unvisited neighbor if any or #f otherwise<br> 'member?' test's if a node is in the visited list </p> <p>The Graph representation is using adjacent made using references to nodes with letrec so that's why I use force in 'neighbors': Eg:<br> (letrec ([node1 (list "NY" (delay (list node2 node3)))],where node2 and node3 are defined as node1 </p> <p>The problem witch I'm dealing with is that my visited lists looses track of some of the nodes I visited when I come out of recursion,How can I fix this ?</p>

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