邻接表的BFS

import java.util.Arrays;
import java.util.LinkedList;

class Vertex {

	public char v;// vertex
	private LinkedList<Vertex> nextList = null;// 与v相邻的vertex集合
	public int color;// 0:white 1:gray 2:black
	private int index;

	// constructor
	Vertex(char ch) {
		this.setV(ch);
		this.setColor(0);
	}

	// 添加相邻顶点
	public void addAdjVertex(Vertex adjVertex) {
		if (nextList == null) {
			nextList = new LinkedList<Vertex>();
		}
		nextList.add(adjVertex);
	}

	// 取得相邻顶点链表
	public LinkedList<Vertex> getNextList() {
		return nextList;
	}

	public int getIndex() {
		return index;
	}

	public void setIndex(int index) {
		this.index = index;
	}

	public char getV() {
		return v;
	}

	public void setV(char v) {
		this.v = v;
	}

	public int getColor() {
		return color;
	}

	public void setColor(int color) {
		this.color = color;
	}
}

class AdjTabGraph {
	private final static int MAX_VERTEX_NUM = 20;// 缺省顶点数
	private Vertex[] vertexSet;// 顶点集合
	private boolean isDirected;// 是否有向
	private int nVertexs;// 顶点实际个数
	private LinkedList<Vertex> queue;
	private int[] distance;// 源顶点与顶点u的距离为distance[u]

	// no-args constructor
	AdjTabGraph() {
		this(MAX_VERTEX_NUM, false);
	}

	// have-args constructor
	AdjTabGraph(int vertexNum, boolean flag) {
		vertexSet = new Vertex[vertexNum];
		isDirected = flag;
		nVertexs = 0;
	}

	// 添加顶点
	public void addVertex(Vertex v) {
		vertexSet[nVertexs] = v;
		vertexSet[nVertexs].setIndex(nVertexs);
		nVertexs++;
	}

	// 添加边
	public void addEdge(int startIndex, int endIndex) {
		vertexSet[startIndex].addAdjVertex(vertexSet[endIndex]);
		if (!isDirected) {
			vertexSet[endIndex].addAdjVertex(vertexSet[startIndex]);
		}
	}

	// bfs
	public void breadthFirstSearch(int index) {
		distance = new int[this.nVertexs];
		Arrays.fill(distance, Integer.MAX_VALUE);
		vertexSet[index].setColor(1);
		distance[index] = 0;
		queue = new LinkedList<Vertex>();
		queue.add(vertexSet[index]);
		while (!queue.isEmpty()) {
			Vertex u = queue.removeFirst();
			System.out.print("顶点" + u.getV() + "  ");
			for (int i = 0; i < u.getNextList().size(); i++) {
				Vertex ui = u.getNextList().get(i);
				if (ui.getColor() == 0) {
					ui.setColor(1);
					distance[ui.getIndex()] = distance[u.getIndex()] + 1;
					queue.add(ui);
				}
			}
			u.setColor(2);
		}
	}
}

public class Graph {

	public static void main(String[] args) {

		AdjTabGraph graph = new AdjTabGraph(7, false);

		graph.addVertex(new Vertex('A'));
		graph.addVertex(new Vertex('B'));
		graph.addVertex(new Vertex('C'));
		graph.addVertex(new Vertex('D'));
		graph.addVertex(new Vertex('E'));
		graph.addVertex(new Vertex('F'));
		graph.addVertex(new Vertex('G'));

		graph.addEdge(0, 1);
		graph.addEdge(0, 2);
		graph.addEdge(0, 3);
		graph.addEdge(1, 5);
		graph.addEdge(1, 4);
		graph.addEdge(2, 3);
		graph.addEdge(2, 6);
		graph.addEdge(3, 5);
		graph.addEdge(3, 6);

		graph.breadthFirstSearch(4);

	}
}