图的DFS和BFS JAVA实现

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图的深度优先遍历 和 广度优先遍历

参考资料：印度一大哥写的 数据结构和算法的java版本

    其中图用的 一个顶点的数组 和一个关系的数组表示

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.Stack;

/**
 * 功能 :
 * date : 2018-06-19 09:57
 *
 * @author : zcwang
 * @version : 0.0.4-snapshot
 * @since : JDK 1.8
 */
public class Graph {
    private static final Logger LOGGER = LoggerFactory.getLogger(Graph.class);

    static class Vertex {
        public String lab;
        public boolean visited;

        public Vertex(final String lab) {
            this.lab = lab;
            this.visited = false;
        }
    }

    private final int maxVertices = 20;
    private final Vertex[] vertices;
    private final int[][] adjVertex;
    private int vertexCount;
    private final Stack<Integer> stack;

    public Graph() {
        this.vertices = new Vertex[this.maxVertices];
        this.adjVertex = new int[this.maxVertices][this.maxVertices];
        this.vertexCount = 0;
        this.stack = new Stack<>();
        for (int i = 0; i < this.maxVertices; i++) {
            for (int j = 0; j < this.maxVertices; j++) {
                this.adjVertex[i][j] = 0;
            }
        }
    }

    public void addVertex(final String lab) {
        this.vertices[this.vertexCount++] = new Vertex(lab);
    }

    public void addEdge(final int start, final int end) {
        if (start >= 0 && start < this.vertexCount && end >= 0 && end < this.vertexCount) {
            this.adjVertex[start][end] = 1;
            this.adjVertex[end][start] = 1;
        }
    }

    public void displayVertex(final int v) {
        System.out.println(this.vertices[v].lab);
    }

    public int getAdjUnvisitedVertex(final int v) {
        for (int i = 0; i < this.vertexCount; i++) {
            if (this.adjVertex[v][i] == 1 && this.vertices[i].visited == false) {
                return i;
            }
        }
        return -1;
    }

    public void dfs() {
        this.stack.push(0);
        displayVertex(0);
        this.vertices[0].visited = true;
        while (!this.stack.isEmpty()) {
            final int v = getAdjUnvisitedVertex(this.stack.peek());
            if (v == -1) {
                this.stack.pop();
            } else {
                displayVertex(v);
                this.vertices[v].visited = true;
                this.stack.push(v);
            }
        }
        for (int i = 0; i < this.vertexCount; i++) {
            this.vertices[i].visited = false;
        }
    }

    public void bfs() {
        final LLQueue<Integer> queue = new LLQueue<>();
        queue.enQueue(0);
        this.vertices[0].visited = true;
        displayVertex(0);
        while (!queue.isEmpty()) {
            final int v = queue.deQueue();
            int result;
            while ((result = getAdjUnvisitedVertex(v)) != -1) {
                this.vertices[result].visited = true;
                displayVertex(result);
                queue.enQueue(result);
            }
        }
        for (int i = 0; i < this.vertexCount; i++) {
            this.vertices[i].visited = false;
        }
    }

    public static void main(final String[] args) {
        final Graph graph = new Graph();

        graph.addVertex("A");
        graph.addVertex("B");
        graph.addVertex("C");
        graph.addVertex("D");
        graph.addVertex("E");
        graph.addVertex("F");
        graph.addVertex("G");
        graph.addVertex("H");

        graph.addEdge(0, 1);
        graph.addEdge(1, 2);
        graph.addEdge(2, 3);
        graph.addEdge(2, 4);
        graph.addEdge(4, 5);
        graph.addEdge(4, 6);
        graph.addEdge(4, 7);
        graph.addEdge(1, 7);
        System.out.println("dfs:");
        graph.dfs();
        System.out.println("bfs:");
        graph.bfs();
    }
}