#include <stdio.h>
#include <stdlib.h>

#define MaxVertexNum 50

typedef struct node *EdgeNode;
typedef struct vnode *VertexNode;
typedef struct graph *ALGraph;

struct node
{						//邊表節點
	int adjvex;			//鄰接點域
	EdgeNode next;		//鏈域
};

struct vnode
{						//頂點表節點
	int vertex;			//頂點域
	EdgeNode firstedge; //邊表頭指標
};

struct graph
{
	struct vnode *adjlist;
	int n;				//圖中當前頂點數
	int e;				//圖中當前邊數
};

void CreatALGraph(ALGraph G)
{
	int i, j, k;
	int a;
	EdgeNode s;			//定義邊表節點
	printf("請輸入頂點數和邊數:\n");
	scanf("%d %d", &i, &j);
	G->n = i;
	G->e = j;
	printf("請輸入頂點編號：\n");
	for (i = 1; i <= G->n; i++)		//建立頂點表
	{
		scanf("%d", &a);
		G->adjlist[i].vertex = a;	//讀入頂點資訊
		G->adjlist[i].firstedge = NULL;	//邊表頭指標置為空
	}
	
	printf("請輸入由兩個定點構成的邊，示例：0 1\n");
	for (k = 0; k < G->e; k++)
	{
		scanf("%d %d", &i, &j);		//讀入邊(Vi, Vj)的頂點對應的序號
		s = malloc(sizeof(struct node));	//生成邊表節點
		s->adjvex = j;
		s->next = G->adjlist[i].firstedge;
		G->adjlist[i].firstedge = s;	//將新節點*s插入頂點Vi的邊表頭部
		/*若建立為無向圖，則新增下面的程式碼*/
		/*
		s = malloc(sizeof(struct node));
		s->adjvex = i;
		s->next = G->adjlist[j].firstedge;
		G->adjlist[j].firstedge = s;
		*/
	}
}


int main()
{
	int i, j;
	ALGraph G = malloc(sizeof(struct graph));
	G->adjlist = (struct vnode *)malloc(sizeof(struct vnode) * MaxVertexNum);
	CreatALGraph(G);

	for (i = 1; i <= G->n; i++)
	{
		while (G->adjlist[i].firstedge)
		{
			printf("%d -> ", G->adjlist[i].vertex);
			printf("%d\n", G->adjlist[i].firstedge->adjvex);
			G->adjlist[i].firstedge = G->adjlist[i].firstedge->next;
		}
	}
	
	return 0;
}