基于Java实现的十字链表（用来表示有向图）

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数据结构+算法=程序

有向图（侵删，引用自http://blog.csdn.net/yao_zi_jie/article/details/54580283）：
这里写图片描述

数据结构类——顶点：

public class Vertex<E,T>  {    E data;    Edge<T> firstIn;    Edge<T> firstOut;    public Vertex(E data) {        this.data = data;    }}

数据结构类——边：

public class Edge<E> {    E data;    int fromVertexIndex;    int toVertexIndex;    Edge<E> nextSameFromVertex;    Edge<E> nextSameToVertex;    public Edge(E data, int fromVertexIndex, int toVertexIndex) {        this.data = data;        this.fromVertexIndex = fromVertexIndex;        this.toVertexIndex = toVertexIndex;    }}

算法类：

package com.my;import java.util.ArrayList;import java.util.List;public class Main {    public static void insertEdge(Edge<Integer> edge, List<Vertex<Integer, Integer>> vertexList) {        int fromVertexIndex = edge.fromVertexIndex;        int toVertexIndex = edge.toVertexIndex;        Vertex<Integer, Integer> fromVertex = vertexList.get(fromVertexIndex);        Vertex<Integer, Integer> toVertex = vertexList.get(toVertexIndex);        if (fromVertex.firstOut == null) {            //插入到顶点的出边属性            fromVertex.firstOut = edge;        } else {            // 插入到edge的nextSameFromVertex属性            Edge<Integer> tempEdge = fromVertex.firstOut;            //找到最后一个Edge            while (tempEdge.nextSameFromVertex != null) {                tempEdge = tempEdge.nextSameFromVertex;            }            tempEdge.nextSameFromVertex = edge;         }        if (toVertex.firstIn == null) {            //插入到顶点的入边属性            toVertex.firstIn = edge;                    } else {            // 插入到edge的nextSameToVertex属性            Edge<Integer> tempEdge = toVertex.firstIn;            //找到最后一个Edge            while (tempEdge.nextSameToVertex != null) {                tempEdge = tempEdge.nextSameToVertex;            }            tempEdge.nextSameToVertex = edge;         }    }    public static void printVertexAndEdges(List<Vertex<Integer, Integer>> list) {        for (Vertex<Integer, Integer> vertex : list) {            //输出入度            String infoIn = String.format("vertex: %3d - its in-edge are: ", vertex.data);            Edge<Integer> edge = vertex.firstIn;            while (edge != null) {                infoIn += String.format("(from: %d, to: %d, data: %d)", edge.fromVertexIndex, edge.toVertexIndex, edge.data);                edge = edge.nextSameToVertex;            }            System.out.println(infoIn);            //输出出度            String infoOut = String.format("vertex: %3d - its out-edge are: ", vertex.data);            Edge<Integer> edgeOut = vertex.firstOut;            while (edgeOut != null) {                infoOut += String.format("(from: %d, to: %d, data: %d)", edgeOut.fromVertexIndex, edgeOut.toVertexIndex, edgeOut.data);                edgeOut = edgeOut.nextSameFromVertex;            }            System.out.println(infoOut);        }    }    public static void main(String[] args) {        int vertexNumber = 12;        int edgeNumber = 21;        // 检查边的数量是否正确        // 有向完全图        int maxEdgeNumber = vertexNumber*(vertexNumber-1);         if (edgeNumber < 0 || edgeNumber > maxEdgeNumber) {            return;        }        // 输入有向图数据        // 1. 先输入顶点，暂时令firstIn， firstOut为null;        ArrayList<Vertex<Integer, Integer>> vertexList = new ArrayList<>();        for (int i=0; i<vertexNumber; i++) {            Vertex<Integer, Integer> v = new Vertex<>(i);            vertexList.add(v);        }         // 2. 输入边        // 二维数组，每一行两个元素，分别是起点和终点的下标        @SuppressWarnings("serial")        List<Edge<Integer>> rawEdgeList = new ArrayList<Edge<Integer>>(){{            add(new Edge<Integer>(9, 0, 1));            add(new Edge<Integer>(7, 0, 2));            add(new Edge<Integer>(3, 0, 3));            add(new Edge<Integer>(2, 0, 4));            add(new Edge<Integer>(4, 1, 5));            add(new Edge<Integer>(2, 1, 6));            add(new Edge<Integer>(1, 1, 7));            add(new Edge<Integer>(2, 2, 5));            add(new Edge<Integer>(7, 2, 6));            add(new Edge<Integer>(11, 3, 7));            add(new Edge<Integer>(11, 4, 6));            add(new Edge<Integer>(8, 4, 7));            add(new Edge<Integer>(6, 5, 8));            add(new Edge<Integer>(5, 5, 9));            add(new Edge<Integer>(4, 6, 8));            add(new Edge<Integer>(3, 6, 9));            add(new Edge<Integer>(5, 7, 9));            add(new Edge<Integer>(6, 7, 10));            add(new Edge<Integer>(4, 8, 11));            add(new Edge<Integer>(2, 9, 11));            add(new Edge<Integer>(5, 10, 11));        }};        for (Edge<Integer> edge : rawEdgeList) {                    insertEdge(edge, vertexList);        }        //遍历顶点，输出每个顶点的出边和入边        printVertexAndEdges(vertexList);    }}

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