用邻接矩阵表示图（代码）和简化版代码

//用邻接矩阵表示图
#include <stdio.h>
#include <stdlib.h>
#define MaxVertexNum 20
 
typedef int WeightType;
typedef char DataType;
typedef struct GNode *PtrToGNode;
typedef PtrToGNode MGraph;        //以邻接矩阵存储的图类型
 
struct GNode {
    int Nv;        //顶点数
    int Ne;        //边数
    WeightType G[MaxVertexNum][MaxVertexNum];
    DataType Data[MaxVertexNum];    //存顶点的数据
};
 
 
 
//初始化一个有VertexNUm个顶点但没有边的图
typedef int Vertex;    //用顶点下标表示顶点，为整型
MGraph CreateGraph(int VertexNum)
{
    Vertex v, w;
    struct GNode* Graph;
    Graph = (MGraph)malloc(sizeof(struct GNode));
    Graph ->Nv = MaxVertexNum;
    Graph ->Ne = 0;
 
    //这里的默认编号从0开始，到（Graph->Nv - 1)
    for (v = 0; v < Graph->Nv; v++)
    for (w = 0; w < Graph->Ne; w++)
        Graph->G[v][w] = 0;
 
    return Graph;
}
 
//向MGraph中插入边
typedef struct ENode *PtrToENode;
struct ENode {
    Vertex v1, v2;        //有向边<v2, v1>
    WeightType Weight;    //权重
};
typedef PtrToENode Edge;
 
void InsertEdge(MGraph Graph, Edge E)
{
    //插入边<v1, v2>
    Graph->G[E -> v1][E->v2] = E->Weight;
 
    //插入边<v2, v1>
    Graph->G[E->v2][E->v1] = E->Weight;
}
 
//完整地建立一个MGraph
MGraph BuildGraph()
{
    MGraph Graph;
    Edge E;
    Vertex V;
    int Nv, i;
    scanf_s("%d", &Nv);
    Graph = CreateGraph(Nv);
    scanf_s("%d", &(Graph->Ne));
    if (Graph->Ne != 0)
    {
        E = (Edge)malloc(sizeof(struct ENode));
        for (i = 0; i < Graph->Ne; i++)
            scanf_s("%d %d %d", &E->v1, &E->v2, &E->Weight);
        InsertEdge(Graph, E);
    }
 
    //
    for (V = 0; V < Graph->Nv; V++)
        scanf_s(" %c", Graph->Data[V]);
 
    return Graph;
}
 
 
 
int main()
{
 
 
    return 0;
}

简化版：

//用邻接矩阵表示图
#include <stdio.h>
#include <stdlib.h>
 
#define MaxN 20
int G[MaxN][MaxN], Nv, Ne;
void BuildGraph()
{
    int i , j, v1, v2, w;
    scanf("%d", &Nv);
 
    for (i = 0; i < Nv; i++)
    for (j = 0; j < Nv; j++)
        G[i][j] = 0;
    scanf_s("%d", &Ne);
    for (i = 0; i < Ne; i++)
    {
        scanf_s("%d %d %d", &v1, &v2, &w);
        
        G[v1][v2] = w;        //InsertEdge
        G[v2][v1] = w;
    }
}