Question

Implement a depth-first search of a graph using a recursive function. The result should print the nodes along the path. Use the following node class.

/*
 * Each node permits iteration to the adjoining nodes.
 */
class Node implements Iterable {
    public String getName();
    ...
};  

/*
 * Return whether a path can be found to the goal.
 * Return null if no path can be found.
 */
List findPath(Node from, Node to, Set visited, List sofar) {
   ...
}

IN JAVA

Answer 1

        /*
         * Return whether a path can be found to the goal.
         * Return null if no path can be found.
         */
        List<Node> findPath(Node from, Node to, Set<Node> visited, List<Node> sofar) {
                
                // If the destination node is same as the src node.
                if(from == to) {
                        return sofar;
                }
                
                // Else, We need to go through the neighbors one by one.
                for(Node neighbor: from) {
                        
                        // If the neighbor is not visited yet
                        if(!visited.contains(neighbor)) {
                                
                                // Create a copy of the visited set and add the new node
                                // to the path
                                TreeSet<Node> visitedCopy =new TreeSet<>(visited);
                                visitedCopy.add(neighbor);
                                
                                ArrayList<Node> sofarCopy = new ArrayList<>(sofar);
                                sofarCopy.add(neighbor);
                                
                                // DFS here.
                                List<Node> result = findPath(neighbor, to, visitedCopy, sofarCopy);
                                if(result != null) {
                                        return result;
                                }
                        }
                }
                
                // If we reached here, then no neighbor path has succeeded.             
                return null;
        }

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