数据结构-图的邻接表

typedef struct Path         //定义边表节点
{
    int placeNum;          //存储顶点下标
    int distance;          //权重值
    struct Path* next;     //边指针
} Path;

typedef struct Place   /*顶点表节点*/
{
    string data; //顶点存的数据
    Path* head; //指向一个邻接点链表（即边表）
} Place,PlaceList[MAXVEX];

typedef struct
{
    PlaceList PlaceList;
    int numVertexes,numEdges;
} Graph;

例如下面的图

利用邻接表表示（以0这个点为例）

图的PlaceList数组存了图中五个节点

0的节点跟1,2,3节点是相连的，所以他的邻接点链表（也就是边链表）有三个有值节点，分别表示1,2,3这三个点以及他们与0点的距离

可以根据下面这个例子理解一下

这个例子是输入各地点以及相连的距离，可以把图存入文件

#include<iostream>
#include<stdio.h>
#include<stdlib.h>
#define MAXVEX 100
#define true 1

using namespace std;


typedef struct Path         //定义边表节点
{
    int placeNum;           //存储顶点下标
    int distance;           //权重值
    struct Path* next;      //边指针
} Path;

typedef struct Place   /*顶点表节点*/
{
    string introduce;
    string data;
    Path* head;
} Place,PlaceList[MAXVEX];

typedef struct
{
    PlaceList PlaceList;
    int numVertexes,numEdges;
} Graph;


void CreatGraph(Graph *g)
{
    int i,j,k;
    int distance;
    Path *e,*e2;
    cout<<"输入图的顶点数与边数："<<endl;
    cin>> g->numVertexes>> g->numEdges;
    string name;
    //gettchar();
    for(i=0; i<g->numVertexes; i++)
    {
        cout<<"第"<<i+1<<"个地点名称"<<endl;
        cin>>g->PlaceList[i].data;            //获取顶点值，
        g->PlaceList[i].head = NULL;    //将边表置为空
    }
    cout<<"回车进入边的输入"<<endl;
    getchar();
    getchar();
    system("cls");

    for(i=0; i<g->numVertexes; i++)
    {
        cout<<"编号："<<i<<" 地点："<<g->PlaceList[i].data<<endl;
    }

    for(k=0; k<g->numEdges; k++)
    {
        cout<<"输入边(两个顶点)及权值"<<endl;
        cin>>i>>j>>distance;           //输入i,j 在图中有i--j
        e=(Path*)malloc(sizeof(Path));
        e->placeNum = j;
        e->distance = distance;
        e->next = g->PlaceList[i].head;   //头插法建立边表
        g->PlaceList[i].head= e;

        e2=(Path*)malloc(sizeof(Path));
        e2->placeNum = i;
        e2->distance = distance;
        e2->next = g->PlaceList[j].head;
        g->PlaceList[j].head= e2;

    }
}

void writeToFile(Graph g)//如果想涉及把图存入文件，可以留着此函数
{
    FILE *fw = fopen("place.txt","w+");
    int i;
    for(i=0; i<g.numVertexes; i++)
    {

        char  num[100];
        itoa(i,num,10);
        char *data =(char*) g.PlaceList[i].data.data();
        fprintf(fw,num);
        fprintf(fw,"\t");
        fprintf(fw,data);
        fprintf(fw,"\t");//结束写点信息
        //开始写边
        Path* current = g.PlaceList[i].head;
        if(current==NULL)
        {
            fprintf(fw,"\n");
        }
        else
        {
            while(current!=NULL)
            {
                char placeNum[100];
                itoa(current->placeNum,placeNum,10);
                char distance[100];
                itoa(current->distance,distance,10);
                fprintf(fw,placeNum);
                fprintf(fw,"\t");
                fprintf(fw,distance);
                fprintf(fw,"\t");
                current = current->next;
            }
            fprintf(fw,"\n");

        }
    }
    fclose(fw);
    cout<<"写出成功！"<<endl;
}

void showPath(Graph g)
{
    Path* current;

    for(int j=0; j<g.numVertexes; j++)
    {
        if(g.PlaceList[j].head==NULL)
        {
            break;
        }
        else
        {
            current = g.PlaceList[j].head;
            while(current!=NULL)
            {
                cout<<g.PlaceList[j].data<<"----"<<g.PlaceList[current->placeNum].data<<": "<<current->distance<<endl;
                current = current->next;
            }
        }
    }
}

void showPlace(Graph g)
{
    for(int i=0; i<g.numVertexes; i++)
    {
        cout<<"第"<<i+1<<"个地点名称:"<<g.PlaceList[i].data<<endl;
    }
}

int main()
{
    Graph g;
    int num = 0;
    do
    {
        cout<<"*************************************\n";
        cout<<"*              菜单                 *\n";
        cout<<"*          1.显示地点               *\n";
        cout<<"*          2.显示路径               *\n";
        cout<<"*          3.写入文件               *\n";
        cout<<"*          4.初始化图               *\n";
        cout<<"*          5.退出                   *\n";
        cout<<"*************************************\n";
        cin>>num;
        {
            switch(num)
            {
            case 1:
            {
                showPlace(g);
                break;
            }
            case 2:
            {
                showPath(g);
                break;

            }
            case 3:
            {
                writeToFile(g);
                break;
            }
            case 4:
            {
                CreatGraph(&g);
                break;
            }
            default:
                break;
            }
        }
        cout<<"按回车继续....";
        getchar();
        getchar();
        system("cls");
    }
    while(1 == num|| 2 == num || 3 == num ||4 == num);

    return 0;
}