/**
 * public class GraphNode {
    int label;
    List<GraphNode> neighbors;
    GraphNode(int x) { label = x; neighbors = new ArrayList<GraphNode>(); }
}
 */
public class graphTravel {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        GraphNode graph = new GraphNode(0);
        List<GraphNode> neighbors = new ArrayList<GraphNode>();
        graph.neighbors = neighbors;
        
        GraphNode g1 = new GraphNode(1);
        GraphNode g2 = new GraphNode(2);
        GraphNode g3 = new GraphNode(3);
        neighbors.add(g1);
        neighbors.add(g2);
        neighbors.add(g3);
        
        List<GraphNode> neighbors1 = new ArrayList<GraphNode>();
        g1.neighbors=neighbors1;
        neighbors1.add(new GraphNode(4));
        neighbors1.add(new GraphNode(5));
                
        Map<GraphNode,Boolean> map = new HashMap<GraphNode,Boolean>();
        System.out.println("深度优先遍历");
        DepthFirstTravel(graph,map);
        
        System.out.println("广度优先遍历");
        BroadFirstTravel(graph);
    }
    
    /**
     * 深度优先遍历，递归实现,需map判断是否访问过
     */
    public static void DepthFirstTravel(GraphNode graph,Map<GraphNode,Boolean> map){
        if(graph == null)return;
        System.out.println(graph.label);
        map.put(graph, true);
        List<GraphNode> neighbors = graph.neighbors;
        for(GraphNode n:neighbors){
            if(!map.containsKey(n)){
                DepthFirstTravel(n,map);
            }
        }
    }
    
    /**
     * 广度遍历，用队列实现,需要布尔map判断是否访问过
     */
    public static void BroadFirstTravel(GraphNode graph){
        if(graph == null)return;
        Map<GraphNode,Boolean> map = new HashMap<GraphNode,Boolean>();
        Queue<GraphNode> queue = new ArrayDeque<GraphNode>();
        queue.offer(graph);
        map.put(graph, true);
        GraphNode n = null;
        while(!queue.isEmpty()){
            n = queue.poll();//出队
            if(n!=null && !map.containsKey(n)){
                System.out.println(n.label);
                map.put(n, true);
                for(GraphNode ch:n.neighbors){
                    queue.offer(ch);//入队
                }
            }
        }					
    }
}