/* 無向圖的鄰接表法建立圖的C程式碼實現 */

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

#define MaxSize 20   //圖頂點的最大數量

typedef char VertexType;

//全域性變數，記錄圖的結點的數量
int VertexNum;

//定義圖頂點
typedef struct GraphNode {
	VertexType ver;
	struct GraphNode *next;
}GraphNode;

//用鄰接表法建立圖
void CreateGraph( GraphNode **g )
{
	VertexType ch;						//用來接收頂點名稱
	int i = 0;
	GraphNode *p, *q;
	(*g) = (GraphNode *)malloc(sizeof(GraphNode)*MaxSize);//分配一個結構體陣列

	printf("請輸入圖的頂點:\n");		//儲存圖的頂點
	scanf("%c", &ch);
	while( '\n' != ch ) {
		(*g)[i].ver = ch;
		(*g)[i].next = NULL;
		i++;
		scanf("%c", &ch);
	}
	
	VertexNum = i;						//記錄頂點數
	
	for( i=0; i<VertexNum; i++ ) {		//儲存圖的邊資訊
		q = (*g)+i;
		printf("請輸入頂點 %c 的鄰接頂點:\n", q->ver );
		scanf("%c", &ch);
		while( '\n' != ch ) {
			p = (GraphNode *)malloc(sizeof(GraphNode));
			p->ver = ch;
			q->next = p;
			q = p;
			q->next = NULL;
			scanf("%c", &ch);
		}
	}
}

//列印鄰接表法建立的圖
void PrintGraph( GraphNode *g )
{
	GraphNode *p;
	printf("圖的頂點為:\n");		//列印頂點
	for( int i=0; i<VertexNum; i++ )
		printf("%c ", g[i].ver);
	printf("\n");

	printf("圖的頂點以及其對應的鄰接頂點為:\n");  //列印鄰接點
	for( i=0; i<VertexNum; i++ ) {
		printf("%c :", g[i].ver);
		p = g[i].next;
		while( NULL != p ) {
			printf("%c ", p->ver);
			p = p->next;
		}
		printf("\n");
	}
}

int main()
{
	GraphNode *g;

	CreateGraph( &g );

	PrintGraph( g );

	return 0;
}
 

測試的圖：

測試結果