Java實現圖的深度和廣度優先遍曆演算法

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概述：

  近期要學習寫網路爬蟲。所以把圖的深度和廣度搜尋都再溫習一下。

圖結構展示：

實現過程：首先，我們來看看圖結構在代碼中的實現。有三塊邏輯：
1.圖中的節點：

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>();}}/** * 給當前節點加入一條邊 * GraphNode * @param edge * 加入的邊 */public void addEdgeList(GraphEdge edge) {edgeList.add(edge);}public String getLabel() {return label;}}

 
2.圖中的邊：

 

public class GraphEdge {private GraphNode nodeLeft;private GraphNode nodeRight;/** * @param nodeLeft * 邊的左端 * @param nodeRight * 邊的右端 */public GraphEdge(GraphNode nodeLeft, GraphNode nodeRight) {this.nodeLeft = nodeLeft;this.nodeRight = nodeRight;}public GraphNode getNodeLeft() {return nodeLeft;}public GraphNode getNodeRight() {return nodeRight;}}

 
3.把節點和邊組合成一個圖結構：

 

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;}}

 
有了圖的結構，我們就能夠進行一些實際的操作了。
深度優先搜尋：

 

public class DFSearch {/** * 深度遍曆 * DFSearch * @param node * 當前節點 * @param visited * 被訪問過的節點列表 */public void searchTraversing(GraphNode node, List<GraphNode> visited) {// 推斷是否遍曆過if (visited.contains(node)) {return;}visited.add(node);System.out.println("節點：" + node.getLabel());for (int i = 0; i < node.edgeList.size(); i++) {searchTraversing(node.edgeList.get(i).getNodeRight(), visited);}}}

 
廣度優先搜尋：

 

public class BFSearch {/** * 廣度優先搜尋 * BFSearch * @param node * 搜尋的入口節點 */public void searchTraversing(GraphNode node) {List<GraphNode> visited = new ArrayList<GraphNode>(); // 已經被訪問過的元素Queue<GraphNode> q = new LinkedList<GraphNode>(); // 用隊列存放依次要遍曆的元素q.offer(node);while (!q.isEmpty()) {GraphNode currNode = q.poll();if (!visited.contains(currNode)) {visited.add(currNode);System.out.println("節點：" + currNode.getLabel());for (int i = 0; i < currNode.edgeList.size(); i++) {q.offer(currNode.edgeList.get(i).getNodeRight());}}}}}

 

執行結果：

原始碼下載：

http://download.csdn.net/detail/u013761665/8968443

Java實現圖的深度和廣度優先遍曆演算法