java 实现DFS和BFS

 

 摘抄自：http://blog.csdn.net/lemon_tree12138/article/details/47319659

 1.图中的节点：

 

 public class GraphNode {

 public List<GraphEdge> edgeList = null;

 

 private String label = "";

 

 public GraphNode(String label) {

  this.label = label;

  if (edgeList == null) {

   edgeList = new ArrayList<GraphEdge>();//建一个集合为每个节点存储边

  }

 }

 

 /**

  * 给当前节点添加一条边

  * GraphNode

  * @param edge

  *    添加的边

  */

 public void addEdgeList(GraphEdge edge) {

  edgeList.add(edge);

 }

 

 public String getLabel() {

  return label;

 }

}

 2.图中的边：

 public class GraphEdge {

 private GraphNode nodeLeft;

 

 private GraphNode nodeRight;

 /**

  * @param nodeLeft

  *    边的左端

  * @param nodeRight

  *    边的右端

  */

 public GraphEdge(GraphNode nodeLeft, GraphNode nodeRight) {  //

  this.nodeLeft = nodeLeft;

  this.nodeRight = nodeRight;

 }

 public GraphNode getNodeLeft() {

  return nodeLeft;

 }

 public GraphNode getNodeRight() {

  return nodeRight;

 }

 

}

 3.把节点和边组合成一个图结构：

 

 public class MyGraph {

 private List<GraphNode> nodes = null;

 

 public void initGraph(int n) {

  if (nodes == null) {

   nodes = new ArrayList<GraphNode>();

  }

  

  GraphNode node = null;

  for (int i = 0; i < n; i++) {

   node = new GraphNode(String.valueOf(i));

   nodes.add(node);

  }

 }

 

 public void initGraph(int n, boolean b) {

  initGraph(n);

  GraphEdge edge01 = new GraphEdge(nodes.get(0), nodes.get(1));

  GraphEdge edge02 = new GraphEdge(nodes.get(0), nodes.get(2));

  GraphEdge edge13 = new GraphEdge(nodes.get(1), nodes.get(3));

  GraphEdge edge14 = new GraphEdge(nodes.get(1), nodes.get(4));

  GraphEdge edge25 = new GraphEdge(nodes.get(2), nodes.get(5));

  GraphEdge edge26 = new GraphEdge(nodes.get(2), nodes.get(6));

  GraphEdge edge37 = new GraphEdge(nodes.get(3), nodes.get(7));

  GraphEdge edge47 = new GraphEdge(nodes.get(4), nodes.get(7));

  GraphEdge edge56 = new GraphEdge(nodes.get(5), nodes.get(6));

  

  

  nodes.get(0).addEdgeList(edge01);

  nodes.get(0).addEdgeList(edge02);

  nodes.get(1).addEdgeList(edge13);

  nodes.get(1).addEdgeList(edge14);

  nodes.get(2).addEdgeList(edge25);

  nodes.get(2).addEdgeList(edge26);

  nodes.get(3).addEdgeList(edge37);

  nodes.get(4).addEdgeList(edge47);

  nodes.get(5).addEdgeList(edge56);

 }

 

 public void initGraph() {

  initGraph(8, false);

 }

 

 public List<GraphNode> getGraphNodes() {

  return nodes;

 }

}

 啦啦啦啦啦啦啦啦啦啦啦有了图的结构，我们就可以进行一些实际的操作了。

 深度优先搜索（你也是很帮帮的哦）

 public class DFSearch {

 

 /**

  * 深度遍历

  * DFSearch

  * @param node

  *    当前节点

  * @param visited

  *    被访问过的节点列表

  */

 public void searchTraversing(GraphNode node, List<GraphNode> visited) {

  // 判断是否遍历过

  if (visited.contains(node)) {

   return;

  }

  

  visited.add(node);

  System.out.println("节点：" + node.getLabel());//功能处理模块

  for (int i = 0; i < node.edgeList.size(); i++) {

   searchTraversing(node.edgeList.get(i).getNodeRight(), visited);//递归深层次遍历

  }

 }

}

 广度优先搜索：

 public class BFSearch {

 

 /**

  * 广度优先搜索

  * BFSearch

  * @param node

  *    搜索的入口节点

  */

 public void searchTraversing(GraphNode node) {

  List<GraphNode> visited = new ArrayList<GraphNode>(); // 已经被访问过的元素

  Queue<GraphNode> q = new LinkedList<GraphNode>(); // 用队列存放依次要遍历的元素

  q.offer(node);//向队列添加一个元素成功则返回true，如果队列已满则返回false

  

  while (!q.isEmpty()) {

   GraphNode currNode = q.poll();//移除并返回队列头部的元素，如果队列为空则返回null

   if (!visited.contains(currNode)) {

    visited.add(currNode);

    System.out.println("节点：" + currNode.getLabel());

    for (int i = 0; i < currNode.edgeList.size(); i++) {

     q.offer(currNode.edgeList.get(i).getNodeRight());

    }

   }

  }

 }

}