深度优先搜索和广度优先搜索

有两种常用的方法可用来搜索图：即深度优先搜索和广度优先搜索。它们最终都会到达所有连通的顶点。深度优先搜索通过栈来实现，而广度优先搜索通过队列来实现。
深度优先搜索： 下面图中的数字显示了深度优先搜索顶点被访问的顺序。

//用于实现深度优先搜索的栈类
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;
}
}
//用于实现广度优先搜索的队列类
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));
}
}
//顶点类
class Vertex{
public char label;
public boolean wasVisited;
public Vertex(char lab){
label=lab;
wasVisited=false;
}
}
//图类
public class Graph {

private final int MAX_VERTS=20;
private Vertex vertexList[];
private int adjMat[][];
private int nVerts;
private StackX theStack;
private Queue theQueue;

/** Creates a new instance of Graph */
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();
theQueue=new Queue();
}
//增加一个顶点
public void addVertex(char lab){
vertexList[nVerts++]=new Vertex(lab);
}
//增加一条边
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);
}
//深度优先搜索
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;
}
//得到与v顶点邻接且未访问过的顶点标号
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;
}
//广度优先搜索
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;
}
}

}

...{ //用于实现广度优先搜索的队列类 //顶点类 //图类