【数据结构】Java实现图的DFS和BFS

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图的深度优先遍历(DFS)和广度优先遍历(BFS），DFS利用递归来实现比较易懂，DFS非递归就是将需要的递归的元素利用一个栈Stack来实现，以达到递归时候的顺序，而BFS则是利用一个队列Queue来实现。

package DataStructure;import java.util.LinkedList;  import java.util.Queue;  import java.util.Stack;public class Graph {       private int number = 9;      private boolean[] flag;      private String[] vertexs = { "A", "B", "C", "D", "E", "F", "G", "H", "I" };      private int[][] edges = {               { 0, 1, 0, 0, 0, 1, 1, 0, 0 },             { 1, 0, 1, 0, 0, 0, 1, 0, 1 },             { 0, 1, 0, 1, 0, 0, 0, 0, 1 },              { 0, 0, 1, 0, 1, 0, 1, 1, 1 },             { 0, 0, 0, 1, 0, 1, 0, 1, 0 },             { 1, 0, 0, 0, 1, 0, 1, 0, 0 },              { 0, 1, 0, 1, 0, 1, 0, 1, 0 },             { 0, 0, 0, 1, 1, 0, 1, 0, 0 },             { 0, 1, 1, 1, 0, 0, 0, 0, 0 }               };      void DFSTraverse() {          flag = new boolean[number];          for (int i = 0; i < number; i++) {              if (flag[i] == false) {// 当前顶点没有被访问                  DFS(i);              }          }      }      void DFS(int i) {          flag[i] = true;// 第i个顶点被访问          System.out.print(vertexs[i] + " ");          for (int j = 0; j < number; j++) {              if (flag[j] == false && edges[i][j] == 1) {                  DFS(j);              }          }      }      void DFS_Map(){        flag = new boolean[number];        Stack<Integer> stack =new Stack<Integer>();        for(int i=0;i<number;i++){            if(flag[i]==false){                flag[i]=true;                System.out.print(vertexs[i]+" ");                stack.push(i);            }            while(!stack.isEmpty()){                int k = stack.pop();                for(int j=0;j<number;j++){                    if(edges[k][j]==1&&flag[j]==false){                        flag[j]=true;                        System.out.print(vertexs[j]+" ");                        stack.push(j);                        break;                    }                }            }        }    }    void BFS_Map(){        flag = new boolean[number];        Queue<Integer> queue = new LinkedList<Integer>();        for(int i=0;i<number;i++){            if(flag[i]==false){                flag[i]=true;                System.out.print(vertexs[i]+" ");                queue.add(i);                while(!queue.isEmpty()){                    int k=queue.poll();                    for(int j=0;j<number;j++){                        if(edges[k][j]==1&&flag[j]==false){                            flag[j] = true;                            System.out.print(vertexs[j]+" ");                            queue.add(j);                        }                    }                }            }        }    }    public static void main(String[] args) {          Graph graph = new Graph();          System.out.println("DFS递归:");          graph.DFSTraverse();        System.out.println();        System.out.println("DFS非递归:");          graph.DFS_Map();        System.out.println();          System.out.println("BFS非递归:");          graph.BFS_Map();    }  }

程序运行结果：
这里写图片描述

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