一：数组表示法

#include<stdio.h>
#define maxn 100
#define INFINITY 0

typedef struct
{
	int vexs[maxn];
	int arcs[maxn][maxn];
	int vexnum, arcnum;//vexnum为顶点数，arcnum为边数
}Graph;

void init(Graph &g)   //需要传递g的地址使g改变
{
	puts("Enter the vexnume and arcnum");
	scanf("%d%d", &g.vexnum, &g.arcnum);
	puts("Enter the vertex");
	for (int i = 0; i < g.vexnum; i++)
		scanf("%d", &g.vexs[i]);           //构造顶点向量
	for (int i = 0; i < g.vexnum; i++)
		for (int j = 0; j < g.vexnum; j++)
			g.arcs[i][j] = INFINITY;      //用无限表示没有这条边,现在用0打印清楚一点
}
int locate(Graph &g, int v)        //寻找位置，有时顶点不一定是数字而且次序也可能打乱输入
{
	int i;
	for (i = 0; i < g.vexnum; i++)
		if (g.vexs[i] == v)
			return i;
}
void create(Graph &g)
{
	int v1, v2, w,i,j,k;
	for (k = 0; k< g.arcnum; k++)
	{
		puts("Enter the two vertexs of the edge and the value");
		scanf("%d%d%d", &v1, &v2, &w);    //输入一条边依附的顶点和权值
		i = locate(g, v1);  j = locate(g, v2);
		g.arcs[i][j] = g.arcs[j][i]=w;    //无向网
	}
}
void print(Graph &g)
{
	for (int i = 0; i < g.vexnum; i++)
	{
		for (int j = 0; j < g.vexnum; j++)
			printf("%d  ", g.arcs[i][j]);
		printf("\n");
	}
}

int main()
{
	Graph g;
	init(g);
	create(g);
	print(g);
	return 0;
}

二：邻接表

#include<stdio.h>
#include<stdlib.h>
#define maxn 20

typedef struct node    //弧的定义
{
	int adjvex;        //该弧指向的顶点
	struct node *next;
	int data;
}node;
typedef struct vnode
{
	int data;
	node *first;
}vnode,adjust[maxn];
typedef struct
{
	adjust vertices;
	int vexnum, arcnum;
}graph;

void build(graph *g)
{
	puts("Enter the vexnum and arcnum");
	scanf("%d%d", &g->vexnum, &g->arcnum);
	int i;
	for (i = 0; i < g->vexnum; i++)
	{
		printf("Enter very vertices of the list\n");
		scanf("%d", &g->vertices[i].data);
		g->vertices[i].first= NULL;
	}
	puts("Establish every list");
	for (int k = 0; k < g->arcnum; k++)
	{
		int v1, v2;
		printf("Enter the edge:(v1,v2)\n");
		scanf("%d%d", &v1, &v2);
		node *s = (node *)malloc(sizeof(node));
		s->adjvex = v2;
		s->next = g->vertices[v1].first;
		g->vertices[v1].first = s;       //倒序插入链表
		s = (node *)malloc(sizeof(node));//无向图两边都要写
		s->adjvex = v1;
		s->next = g->vertices[v2].first;
		g->vertices[v2].first = s;
	}
}
void print(graph *g)
{
	for (int i = 0; i < g->vexnum; i++)
	{
		printf("%d->", i);
		while (g->vertices[i].first != NULL)
		{
			printf("%d->", g->vertices[i].first->adjvex);
			g->vertices[i].first = g->vertices[i].first->next;
		}
		printf("\n");
	}
}

int main()
{
	graph *g=(graph *)malloc(sizeof(graph));
	build(g);
	print(g);
	return 0;
}