【算法】图的广度优先搜索和深度优先搜索

我们构建一张如下的图：

直接上代码：

package main;

import java.util.ArrayList;

public class Node {
    private String name = "";
    public ArrayList<Node> neighbor = new ArrayList<>();
    public boolean flag = false;

    public Node(String name){
        this.name = name;
    }

    public void addNeighbor(Node... nodes){
        if(nodes != null){
            for(Node temp:nodes){
                neighbor.add(temp);
            }
        }
    }

    public String getName(){
        return name;
    }
}

package main;

import java.util.ArrayList;
import java.util.LinkedList;
import java.util.Queue;
import java.util.Stack;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

public class Main {
    public static void main(String[] args){
        Node a = new Node("A");
        Node b = new Node("B");
        Node c = new Node("C");
        Node d = new Node("D");
        Node e = new Node("E");
        Node f = new Node("F");
        Node g = new Node("G");
        Node h = new Node("H");
        Node i = new Node("I");

        a.addNeighbor(b,f);
        b.addNeighbor(a,g,i,c);
        c.addNeighbor(b,i,d);
        d.addNeighbor(c,i,g,h,e);
        e.addNeighbor(d,h,f);
        f.addNeighbor(a,g,e);
        h.addNeighbor(g,d,e);
        i.addNeighbor(b,c,d);

        //深度优先
        Stack<Node> stack = new Stack<>();
        stack.push(a);
        a.flag = true;
        while(!stack.isEmpty()){
            Node curNode = stack.pop();
            System.out.print(curNode.getName());
            for(Node temp:curNode.neighbor){
                if(temp.flag == false){
                    stack.push(temp);
                    temp.flag = true;
                }
            }
        }
        System.out.println("
");

        a.flag = false;
        b.flag = false;
        c.flag = false;
        d.flag = false;
        g.flag = false;
        e.flag = false;
        f.flag = false;
        h.flag = false;
        i.flag = false;

        //广度优先
        Queue<Node> queue = new LinkedList<>();
        queue.offer(a);
        a.flag = true;
        while(!queue.isEmpty()){
            Node curNode = queue.poll();
            System.out.print(curNode.getName());
            for(Node temp:curNode.neighbor){
                if(temp.flag == false){
                    queue.offer(temp);
                    temp.flag = true;
                }
            }
        }

        System.out.print("
");
    }

}

输出结果分别为：

AFEHDICGB

ABFGICEDH