graph.h

图的邻接距阵与邻接表的转换
#include <stdio.h>
#include <malloc.h>
#define INF 32767       //INF表示∞
typedef int InfoType;
typedef int Vertex;
#define MAXV 50     //最大顶点个数

//以下定义邻接矩阵类型
typedef struct 
{ int nunber;       //顶点编号
InfoType info;     //顶点其他信息
} VertexType;      //顶点类型

typedef struct      //图的定义
{ int edges[MAXV][MAXV];    //邻接矩阵
   int n,e;         //顶点数，弧数
VertexType vexs[MAXV];   //存放顶点信息
} MGraph;       //图的邻接矩阵类型

//以下定义邻接表类型
typedef struct ANode           //弧的结点结构类型
{ int adjvex;              //该弧的终点位置
   InfoType info;           //该弧的相关信息,这里用于存放权值
    struct ANode *nextarc;    //指向下一条弧的指针
} ArcNode;

typedef struct Vnode         //邻接表头结点的类型
{ Vertex data;            //顶点信息
int count;                //存放顶点入度,只在拓扑排序中用
    ArcNode *firstarc;        //指向第一条弧
} VNode;

typedef VNode AdjList[MAXV]; //AdjList是邻接表类型
typedef struct 
{ AdjList adjlist;         //邻接表
    int n,e;                 //图中顶点数n和边数e
} ALGraph;                   //图的邻接表类型

//将邻接矩阵g转换成邻接表G
void MatToList(MGraph g,ALGraph *&G)
{
int i,j,n=g.n;       //n为顶点数
ArcNode *p;
G=(ALGraph *)malloc(sizeof(ALGraph));
// for (i=0;i<n;i++)      //给邻接表中所有头结点的指针域置初值
// G->adjlist[i].firstarc=NULL;
for (i=0;i<n;i++)      //检查邻接矩阵中每个元素
   for (j=n-1;j>=0;j--)
    if (g.edges[i][j]!=0)     //邻接矩阵的当前元素不为0
    {   
      p=(ArcNode *)malloc(sizeof(ArcNode)); //创建一个结点*p
     p->adjvex=j;
     p->info=g.edges[i][j];
     p->nextarc=G->adjlist[i].firstarc;   //将*p链到链表后
     G->adjlist[i].firstarc=p;
    }
G->n=n;G->e=g.e;
}

void ListToMat(ALGraph *G,MGraph &g)
//将邻接表G转换成邻接矩阵g
{
int i,n=G->n;
ArcNode *p;
for (i=0;i<n;i++) 
{ 
   p=G->adjlist[i].firstarc;
     while (p!=NULL) 
   { 
    g.edges[i][p->adjvex]=p->info;
      p=p->nextarc;
   }
}
g.n=n;g.e=G->e;
}
void DispMat(MGraph g)
//输出邻接矩阵g
{
int i,j;
for (i=0;i<g.n;i++)
{
   for (j=0;j<g.n;j++)
    if (g.edges[i][j]==INF)
     printf("%3s","∞");
    else
     printf("%3d",g.edges[i][j]);
   printf("\n");
}
}
void DispAdj(ALGraph *G)
//输出邻接表G
{
int i;
ArcNode *p;
for (i=0;i<G->n;i++)
{
   p=G->adjlist[i].firstarc;
   printf("%3d: ",i);
   while (p!=NULL)
   {
    printf("%3d",p->adjvex); //输出该弧的终点位置
    p=p->nextarc;
   }
   printf("\n");
}
}
//以下主函数用作调试
void main()
{
int i,j;
MGraph g,g1;
ALGraph *G;
int A[6][6]={
   {0,5,0,7,0,0},
   {0,0,4,0,0,0},
   {8,0,0,0,0,9},
   {0,0,5,0,0,6},
   {0,0,0,5,0,0},
   {3,0,0,0,1,0}};
g.n=6;g.e=10;
for (i=0;i<g.n;i++)
   for (j=0;j<g.n;j++)
    g.edges[i][j]=A[i][j];
printf("\n");
printf(" 有向图G的邻接矩阵:\n");
DispMat(g);
G=(ALGraph *)malloc(sizeof(ALGraph));
printf(" 图G的邻接矩阵转换成邻接表:\n");
MatToList(g,G);
DispAdj(G);
printf(" 图G的邻接表转换成邻接邻阵:\n");
for (i=0;i<g.n;i++)
    for (j=0;j<g.n;j++)
    g1.edges[i][j]=0;
ListToMat(G,g1);
DispMat(g1);
printf("\n");
}