(下圖皆來自:java數據結構和算法(第二版))
一、深度優先搜索DFS:
package com.hqy.graph;
class StackX{
private final int SIZE=20;
private int[] st;
private int top;
public StackX(){
st=new int[SIZE];
top=-1;
}
public void push(int j){
st[++top]=j;
}
public int pop(){
return st[top--];
}
public int peek(){
return st[top];
}
public boolean isEmpty(){
return top==-1;
}
}
class Vertex{
public char label;
public boolean wasVisited;
public Vertex(char lab){
label=lab;
wasVisited=false;
}
}
class Graph{
private final int MAX_VERTS=20;
private Vertex vertexList[];
private int adjMat[][];
private int nVerts;
private StackX theStack;
public Graph(){
vertexList=new Vertex[MAX_VERTS];
adjMat=new int[MAX_VERTS][MAX_VERTS];
nVerts=0;
for(int j=0;j<MAX_VERTS;j++){
for(int k=0;k<MAX_VERTS;k++){
adjMat[j][k]=0;
}
}
theStack=new StackX();
}
public void addVertex(char lab){
vertexList[nVerts++]=new Vertex(lab);
}
public void addEdge(int start,int end){
adjMat[start][end]=1;
adjMat[end][start]=1;
}
public void displayVertex(int v){
System.out.print(vertexList[v].label);
}
public void dfs(){
vertexList[0].wasVisited=true;
displayVertex(0);
theStack.push(0);
while(!theStack.isEmpty()){
int v=getAdjUnvisitedVertex(theStack.peek());
if(v==-1){
theStack.pop();
}else{
vertexList[v].wasVisited=true;
displayVertex(v);
theStack.push(v);
}
}
for(int j=0;j<nVerts;j++){
vertexList[j].wasVisited=false;
}
}
public int getAdjUnvisitedVertex(int v){
for(int j=0;j<nVerts;j++){
if(adjMat[v][j]==1&&vertexList[j].wasVisited==false){
return j;
}
}
return -1;
}
}
public class DFSApp {
public static void main(String[] args) {
// TODO Auto-generated method stub
Graph theGraph=new Graph();
theGraph.addVertex('A');
theGraph.addVertex('B');
theGraph.addVertex('C');
theGraph.addVertex('D');
theGraph.addVertex('E');
theGraph.addVertex('F');
theGraph.addEdge(0, 1);
theGraph.addEdge(1, 5);
theGraph.addEdge(0, 5);
theGraph.addEdge(3, 4);
theGraph.addEdge(2, 3);
theGraph.addEdge(2, 5);
theGraph.addEdge(4, 5);
System.out.print("visits:");
theGraph.dfs();
System.out.println();
}
二、廣度優先搜索BFS:
package com.hqy.graph;
class Queue{
private final int SIZE=20;
private int[] queArray;
private int front;
private int rear;
public Queue(){
queArray=new int [SIZE];
front=0;
rear=-1;
}
public void insert(int j){
if(rear==SIZE-1){
rear=-1;
}
queArray[++rear]=j;
}
public int remove(){
int temp=queArray[front++];
if(front==SIZE){
front=0;
}
return temp;
}
public boolean isEmpty(){
return rear+1==front||front+SIZE-1==rear;
}
}
class Vertex2{
public char label;
public boolean wasVisited;
public Vertex2(char lab){
label=lab;
wasVisited=false;
}
}
class Graph2{
private final int MAX_VERTS=20;
private Vertex vertexList[];
private int adjMat[][];
private int nVerts;
private Queue theQueue;
public Graph2(){
vertexList=new Vertex[MAX_VERTS];
adjMat=new int[MAX_VERTS][MAX_VERTS];
nVerts=0;
for(int j=0;j<MAX_VERTS;j++){
for(int k=0;k<MAX_VERTS;k++){
adjMat[j][k]=0;
}
}
theQueue=new Queue();
}
public void addVertex(char lab){
vertexList[nVerts++]=new Vertex(lab);
}
public void addEdge(int start,int end){
adjMat[start][end]=1;
adjMat[end][start]=1;
}
public void displayVertex(int v){
System.out.print(vertexList[v].label);
}
public void bfs(){
vertexList[0].wasVisited=true;
displayVertex(0);
theQueue.insert(0);
int v2;
while(!theQueue.isEmpty()){
int v1=theQueue.remove();
while((v2=getAdjUnvisitedVertex(v1))!=-1){
vertexList[v2].wasVisited=true;
displayVertex(v2);
theQueue.insert(v2);
}
}
for(int j=0;j<nVerts;j++){
vertexList[j].wasVisited=false;
}
}
public int getAdjUnvisitedVertex(int v){
for(int j=0;j<nVerts;j++){
if(adjMat[v][j]==1&&vertexList[j].wasVisited==false){
return j;
}
}
return -1;
}
}
public class BFSApp {
public static void main(String[] args) {
// TODO Auto-generated method stub
Graph2 theGraph=new Graph2();
theGraph.addVertex('A');
theGraph.addVertex('B');
theGraph.addVertex('C');
theGraph.addVertex('D');
theGraph.addVertex('E');
theGraph.addVertex('F');
theGraph.addEdge(0, 1);
theGraph.addEdge(1, 5);
theGraph.addEdge(0, 5);
theGraph.addEdge(3, 4);
theGraph.addEdge(2, 3);
theGraph.addEdge(2, 5);
theGraph.addEdge(4, 5);
System.out.print("visits:");
theGraph.bfs();
System.out.println();
}
}