算法之美-java有权图的表示
直接表示法
测试用例
8 16
4 5 .35
4 7 .37
5 7 .28
0 7 .16
1 5 .32
0 4 .38
2 3 .17
1 7 .19
0 2 .26
1 2 .36
1 3 .29
2 7 .34
6 2 .40
3 6 .52
6 0 .58
6 4 .93
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import java.util.Scanner;
/**
//int num = (new Double(0.999999)).intValue(); //0
//int num = (int）0.999999;//0
Double db = new Double(1);//1.0
int num = db.intValue();
System.out.println(num);//1
* @author Administrator
*18:57:03 18:58:26 18:59:06 19:19:52
*/
public class ListWeigthGraph {
static List<List<Double[]>> totallist;
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
int N = scanner.nextInt();
int M = scanner.nextInt();
totallist = new ArrayList<>();
for(int i=0;i<N;i++) {
totallist.add(new LinkedList<>());
}
for(int i=0;i<M;i++) {
int s = scanner.nextInt();
Double ds = Double.valueOf(s);
int e = scanner.nextInt();
Double de = Double.valueOf(e);
double w = scanner.nextDouble();
totallist.get(s).add(new Double[] {ds,de,w});
//无向图
//totallist.get(e-1).add(new Double[] {de,ds,w});
}
//遍历图的信息
for(int i=0;i<totallist.size();i++) {
for(int j=0;j<totallist.get(i).size();j++) {
Double[] item = totallist.get(i).get(j);
int startIndex = item[0].intValue();
int toIndex = item[1].intValue();
double weight = item[2];
....//业务信息
}
}
}
}
输出：
面向对象表示法
定义有权图的接口
/**
* 18:32:34 18:33:22 18:33:48 18:34:43 18:36:33 18:36:51 18:37:51 18:38:19
* 18:38:56 18:39:56 18:40:29 18:43:18 4:19:45 4:21:38 4:45:25
* @author Administrator
*
*/
public interface WeightedGraph<Weight extends Number & Comparable> {
public int V();
public int E();
public void addEdge(Edge<Weight> e);
void show();
public Iterable<Edge<Weight>> adj(int v);
}
定义边
public class Edge <Weight extends Number & Comparable> implements Comparable<Edge>{
private int a,b;
private Weight weight;
public Edge(int a, int b, Weight weight) {
super();
this.a = a;
this.b = b;
this.weight = weight;
}
public Edge() {
super();
}
public Edge(Edge<Weight> e) {
super();
this.a = e.a;
this.b = e.b;
this.weight = e.weight;
}
public int getV() {
return a;
}
public int getW() {
return b;
}
public Weight getWeight() {
return weight;
}
public int other(int x) {
assert x==a||x==b;
return x==a?b:a;
}
@Override
public String toString() {
return "Edge [a=" + a + ", b=" + b + ", weight=" + weight + "]";
}
@Override
public int compareTo(Edge that) {
// TODO Auto-generated method stub
if(weight.compareTo(that.getWeight())<0) {
return -1;
}else if(weight.compareTo(that.getWeight())>0) {
return 1;
}else
return 0;
}
}定义图
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
/**
* 4:56:59 4:58:00 4:59:44 5:02:54 5:05:41 5:06:10 5:07:38 5:08:56 5:09:42
* @author Administrator
* @param <Weight>
*
*/
public class SparseWeightedGraph<Weight extends Number & Comparable> implements WeightedGraph{
private int n;//结点数
private int m;//边数
private boolean isdirected;
private List<List<Edge<Weight>>> totallist;
public SparseWeightedGraph(int n, boolean isdirected) {
super();
this.n = n;
this.m = 0;
this.isdirected = isdirected;
totallist = new ArrayList<>();
for(int i=0;i<n;i++) {
totallist.add(new LinkedList());
}
}
@Override
public int V() {
// TODO Auto-generated method stub
return n;
}
@Override
public int E() {
// TODO Auto-generated method stub
return m;
}
@Override
public void addEdge(Edge e) {
// TODO Auto-generated method stub
totallist.get(e.getV()).add(new Edge(e));
if(e.getV()!=e.getW()&&!isdirected) {
totallist.get(e.getW()).add(new Edge(e.getW(),e.getV(),e.getWeight()));
}
m++;
}
// 验证图中是否有从v到w的边
public boolean hasEdge( int v , int w ){
assert v >= 0 && v < n ;
assert w >= 0 && w < n ;
for( int i = 0 ; i < totallist.get(v).size() ; i ++ )
if( totallist.get(v).get(i).other(v) == w )
return true;
return false;
}
@Override
// 显示图的信息
public void show(){
for( int i = 0 ; i < n ; i ++ ){
System.out.print("vertex " + i + ":\t");
for( int j = 0 ; j < totallist.get(i).size() ; j ++ ){
Edge e =totallist.get(i).get(j);
System.out.print( "( to:" + e.other(i) + ",wt:" + e.getWeight() + ")\t");
}
System.out.println();
}
}
@Override
public Iterable<Edge<Weight>> adj(int v) {
// TODO Auto-generated method stub
return null;
}
}
读图
import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.Scanner;
import java.util.Locale;
import java.util.InputMismatchException;
import java.util.NoSuchElementException;
/*
* 4:44:46
*/
// 通过文件读取有全图的信息
public class ReadWeightedGraph{
private Scanner scanner;
// 由于文件格式的限制，我们的文件读取类只能读取权值为Double类型的图
public ReadWeightedGraph(WeightedGraph<Double> graph, String filename){
readFile(filename);
try {
int V = scanner.nextInt();
if (V < 0)
throw new IllegalArgumentException("number of vertices in a Graph must be nonnegative");
assert V == graph.V();
int E = scanner.nextInt();
if (E < 0)
throw new IllegalArgumentException("number of edges in a Graph must be nonnegative");
for (int i = 0; i < E; i++) {
int v = scanner.nextInt();
int w = scanner.nextInt();
Double weight = scanner.nextDouble();
assert v >= 0 && v < V;
assert w >= 0 && w < V;
graph.addEdge(new Edge<Double>(v, w, weight));
}
}
catch (InputMismatchException e) {
String token = scanner.next();
throw new InputMismatchException("attempts to read an 'int' value from input stream, but the next token is \"" + token + "\"");
}
catch (NoSuchElementException e) {
throw new NoSuchElementException("attemps to read an 'int' value from input stream, but there are no more tokens available");
}
}
private void readFile(String filename){
assert filename != null;
try {
File file = new File("src/"+filename);
if (file.exists()) {
FileInputStream fis = new FileInputStream(file);
scanner = new Scanner(new BufferedInputStream(fis), "UTF-8");
scanner.useLocale(Locale.ENGLISH);
}
else
throw new IllegalArgumentException(filename + " doesn't exist.");
}
catch (IOException ioe) {
throw new IllegalArgumentException("Could not open " + filename, ioe);
}
}
}
public class Main {
// 测试通过文件读取图的信息
public static void main(String[] args) {
// 使用两种图的存储方式读取testG1.txt文件
String filename = "testG1.txt";
SparseWeightedGraph<Double> g1 = new SparseWeightedGraph<Double>(8, false);
ReadWeightedGraph readGraph1 = new ReadWeightedGraph(g1, filename);
System.out.println("test G1 in Sparse Weighted Graph:");
g1.show();
System.out.println();
}
}输出：
