Java 实现广度优先搜索和深度优先搜索

Java 实现广度优先搜索和深度优先搜索

1. 综述

　　复习算法数据结构，用Java 实现广度优先搜索和深度优先搜索。

2. 代码

要搜索的图为：

Java代码：

package cn.edu.tju.scs;

import java.util.LinkedList;
import java.util.Queue;

public class Search {
    public static boolean [] accessed = new boolean[8];
    public static boolean [] accessed2 = new boolean[8];
    public static ArcNode [] heads = new ArcNode[8];
    public static Queue<Integer> queue = new LinkedList<Integer>();
    
    public static void main(String [] args) {        
        for (int i = 0; i < heads.length; i++) {
            heads[i] = new ArcNode(i + 1);    // 如果节点编号也从0开始就好了，少了很多加一减一的操作
        }
        for (int i = 0; i < accessed.length; i++) {
            accessed[i] = false;            
        }
        heads[0].nextArc = new ArcNode(2);
        heads[0].nextArc.nextArc = new ArcNode(3);
        
        heads[1].nextArc = new ArcNode(1);
        heads[1].nextArc.nextArc = new ArcNode(4);
        heads[1].nextArc.nextArc.nextArc = new ArcNode(5);
        
        heads[2].nextArc = new ArcNode(1);
        heads[2].nextArc.nextArc = new ArcNode(6);
        heads[2].nextArc.nextArc.nextArc = new ArcNode(7);
        
        heads[3].nextArc = new ArcNode(2);
        heads[3].nextArc.nextArc = new ArcNode(8);
        
        heads[4].nextArc = new ArcNode(2);
        heads[4].nextArc.nextArc = new ArcNode(8);
        
        heads[5].nextArc = new ArcNode(3);
        
        heads[6].nextArc = new ArcNode(3);
        
        heads[7].nextArc = new ArcNode(4);
        heads[7].nextArc.nextArc = new ArcNode(5);
        
        BroadFirstSearch(heads);
        DepthFirstSearch(heads);
    }

    private static void BroadFirstSearch(ArcNode[] heads) {
        BroadFirstSearch(heads[0]);
    }

    private static void BroadFirstSearch(ArcNode arcNode) {
        queue.add(arcNode.adjvex);
        accessed2[arcNode.adjvex - 1] = true;
        while (queue.size() > 0) {
            Integer vex = queue.remove();
            ArcNode curNode = heads[vex - 1].nextArc;
            while(curNode != null) {
                if (!accessed2[curNode.adjvex - 1]) {
                    queue.add(curNode.adjvex);
                    accessed2[curNode.adjvex - 1] = true;
                }
                curNode = curNode.nextArc;
            }
            System.out.print(vex);
            if (queue.size() > 0)
                System.out.print(" -> ");
            else
                System.out.println("");
        }
    }

    private static void DepthFirstSearch(ArcNode[] heads) {
        DepthFirstSearch(heads[0]);
    }

    private static void DepthFirstSearch(ArcNode arcNode) {
        ArcNode curNode = heads[arcNode.adjvex-1];
        System.out.print(curNode);
        accessed[curNode.adjvex -1] = true;
        
        curNode = curNode.nextArc;
        while(curNode != null) {
            if (!accessed[curNode.adjvex - 1]){
                System.out.print(" -> ");
                DepthFirstSearch(curNode);
            }
            curNode = curNode.nextArc;
        }
    }
}

输出结果：

（广搜：）1 -> 2 -> 3 -> 4 -> 5 -> 6 -> 7 -> 8
（深搜：）1 -> 2 -> 4 -> 8 -> 5 -> 3 -> 6 -> 7