java实现图的广度优先遍历和深度优先遍历

java实现图的广度优先遍历和深度优先遍历

/**
 * 图的广度优先遍历和深度优先遍历
 */
@Data
@AllArgsConstructor
@NoArgsConstructor
public class GraphBFS {
    private List<Node> nodes;
    private SetMultimap<String, Integer> edgeTable;

    public static void main(String[] args) {
        Set<String> nodes = Sets.newHashSet("A", "B", "C", "D", "E", "F", "G");
        List<String> edges = Lists.newArrayList("A->B","A->C","A->D","B->E","E->F","C->G");
        List<Node> nodeList = nodes.stream().map(node -> {
            Node node1 = new Node();
            node1.setName(node);
            return node1;
        }).collect(Collectors.toList());
        SetMultimap<String, Integer> multimap = HashMultimap.create();
        edges.forEach(edge -> {
            String[] split = edge.split("->");
            String start = split[0];
            String end = split[1];
            int index = getIndex(nodeList, end);
            multimap.put(start, index);
        });


        System.out.println("===================bfs");
        GraphBFS graph = new GraphBFS(nodeList, multimap);
        Node head = new Node("A", Color.WHITE);
        bfs(graph,head);

        System.out.println("===================dfs");
        GraphBFS graphD = new GraphBFS(nodeList, multimap);
        dfs(graphD);
    }

    /**
     * 通过名字获取索引
     * @param nodes
     * @param nodeName
     * @return
     */
    public static   int getIndex(List<Node> nodes,String nodeName) {
        for (int i = 0; i < nodes.size(); i++) {
            if(nodes.get(i).getName().equals(nodeName)){
                return i;
            }
        }
        return -1;
    }

    /**
     * 广度优先遍历
     * @param graph
     * @param headNode
     */
    public static void bfs(GraphBFS graph,Node headNode) {
        Queue<Node> queue = new LinkedList<>();
        List<Node> nodes = graph.getNodes();
        SetMultimap<String, Integer> edgeTable = graph.getEdgeTable();
        for (Node node : nodes) {
            node.setColor(Color.WHITE);
        }
        headNode.setColor(Color.RED);
        System.out.println(headNode);
        queue.add(headNode);
        while (!queue.isEmpty()) {
            Node node1 = queue.remove();
            Set<Integer> integers = edgeTable.get(node1.name);
            for (Integer s : integers) {
                Node node = nodes.get(s);
                if (node.getColor() != Color.RED) {
                    node.setColor(Color.RED);
                    System.out.println(node);
                    queue.add(node);
                }
            }
        }

    }

    /**
     * 深度优先遍历
     * @param graph
     */
    public static void dfs(GraphBFS graph) {
        List<Node> nodes = graph.getNodes();
        for (Node node : nodes) {
            node.setColor(Color.WHITE);
        }
        for (Node node : nodes) {
            if (node.getColor().equals(Color.WHITE)) {
                doDFS(graph,node);
            }
        }

    }

    private static void doDFS(GraphBFS graph,Node node) {
        node.setColor(Color.RED);
        System.out.println(node);
        List<Node> nodes = graph.getNodes();
        SetMultimap<String, Integer> edgeTable = graph.getEdgeTable();
        Set<Integer> integers = edgeTable.get(node.getName());
        for (Integer integer : integers) {
            Node node1 = nodes.get(integer);
            if (node1.getColor().equals(Color.WHITE)) {
                doDFS(graph,node1);
            }
        }

    }

    @Data
    @NoArgsConstructor
    @AllArgsConstructor
    static class Node{
        private String name;
        private Color color;
    }

    enum Color{
        WHITE,RED;
    }
}