本文已参与「新人创作礼」活动，一起开启掘金创作之路。
建立图的邻接矩阵：
package com.answer.tu;
public class DFSBFS {
private char[] mVexs;//顶点集合
private int[][] mMatrix;//邻接矩阵
public DFSBFS(char[] vexs, char[][] edges){
int vlen=vexs.length;
int elen=edges.length;
mVexs=new char[vlen];
for(int i=0;i<vlen;i++){
mVexs[i]=vexs[i];
}
mMatrix=new int[vlen][vlen];
for(int i=0;i<elen;i++){
int pos1=getPos(edges[i][0]);
int pos2=getPos(edges[i][1]);
mMatrix[pos1][pos2]=1;
}
}
private int getPos(char c) {
for(int i=0;i<mVexs.length;i++){
if(mVexs[i]==c){
return i;
}
}return -1;
}
private int nextVertex(int i, int w) {//返回其余的邻接点
for(int j=w+1;j<mVexs.length;j++){//i:H,j:H
if(mMatrix[i][j]==1){
return j;
}
}return -1;
}
private int firstVertex(int i) {//返回第一个邻接节点
for(int j=0;j<mVexs.length;j++){
if(mMatrix[i][j]==1){
return j;
}
}return -1;
}
public void print(){
for(int i=0;i<mMatrix.length;i++){
for(int j=0;j<mMatrix[i].length;j++){
System.out.print(mMatrix[i][j]+" ");
}
System.out.println();
}
}
public static void main(String[] args) {
char[] vexs = {'A', 'B', 'C', 'D','E','F','G','H','I'};
char[][] edges = new char[][]{
{'A', 'B'},
{'A', 'F'},
{'B', 'G'},
{'B', 'C'},
{'B', 'I'},
{'C', 'B'},
{'C', 'I'},
{'C', 'D'},
{'D', 'C'},
{'D', 'I'},
{'D', 'G'},
{'D', 'H'},
{'D', 'E'},
{'E', 'H'},
{'E', 'F'},
{'F', 'G'},
{'F', 'A'},
{'F', 'E'},
{'G', 'H'},
{'G', 'D'},
{'G', 'B'},
{'H', 'G'},
{'H', 'D'},
{'H', 'E'},
{'I', 'B'},
{'I', 'C'}
};
DFSBFS pG;
pG = new DFSBFS(vexs, edges);
pG.print();
pG.DFS();
pG.BFS();
}
}
深度优先遍历：
每次访问完当前节点后首先访问当前节点的第一个邻接节点;
public void DFS(){
boolean[] visited=new boolean[mVexs.length];
System.out.println("DFS:");
for(int i=0;i<mVexs.length;i++){
if(visited[i]==false){
DFS(i,visited);
}
}
System.out.println();
}
private void DFS(int i, boolean[] visited) {
visited[i]=true;
System.out.print(" "+mVexs[i]);
int w=firstVertex(i);//i:A,w:B
while(w>=0){
if(visited[w]==false){
DFS(w,visited);
}
w=nextVertex(i,w);
}
i--;//回退
}
广度优先遍历：
按层遍历；
public void BFS(){
int head=0;
int rear=0;
int[] queue=new int[this.mVexs.length];
boolean[] visited=new boolean[this.mVexs.length];
for (int i = 0; i < mVexs.length; i++){//初始化访问标记
visited[i] = false;
}
System.out.println("BFS:");
for(int i=0;i<mVexs.length;i++){
if(visited[i]==false){
visited[i]=true;
System.out.print(" "+mVexs[i]);
queue[rear++]=i;
}
while(head!=rear){
int j=queue[head++];
int k=firstVertex(j);
while(k>=0){
if(visited[k]==false){
visited[k]=true;
System.out.print(" "+mVexs[k]);
queue[rear++]=k;
}
k=nextVertex(j,k);
}
}
}
}
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