图的创建——邻接表法

#include <iostream>
#include <cstdio>
#include <cstdlib>

using namespace std;

const int VERTEX_NUM = 20;			// 最大允许的顶点数 

// 边表的结点（单链表） 
class EdgeNode {
public:
	int vertexData;
	int weight;
	EdgeNode *next;
}; 

// 顶点表的结点 
class VertexNode {
public:
	int vertexData;
	EdgeNode *firstEdge;
};

// 图的结构 
class Graph {
public:
	VertexNode vertex[VERTEX_NUM];		
	int vertexNum;			// 当前图的顶点数 
	int edgeNum;			// 当前图的边数 
};

void createGraph(Graph &G)
{
	cout << "请输入无向图的顶点数和边数：";
	cin >> G.vertexNum >> G.edgeNum;
	// 读入顶点信息，建立顶点表 
	for (int i = 0; i != G.vertexNum; ++i) {
		cout << "请输入第" << i + 1 << "个顶点的序号：";
		cin >> G.vertex[i].vertexData;
		G.vertex[i].firstEdge = NULL;		// 将边表置位空表 
	}
	// 建立边表 
	for (int k = 0; k != G.edgeNum; ++k) {
		cout << "请输入边（vi, vj）的顶点i、j及权重w：";
		int i, j, w;
		cin >> i >> j >> w;
		EdgeNode *q = (EdgeNode*)malloc(sizeof(EdgeNode));		// 生成边表结点，下同单链表的头插入 
		q->vertexData = j;
		q->weight = w;
		q->next = G.vertex[i].firstEdge;
		G.vertex[i].firstEdge = q;
		// 无向图要再设置另一半 
		EdgeNode *s = (EdgeNode*)malloc(sizeof(EdgeNode));		// 生成边表结点 
		s->vertexData = i;
		s->weight = w;
		s->next = G.vertex[j].firstEdge;
		G.vertex[j].firstEdge = s;
	}
}

int main()
{
	Graph G;
	createGraph(G);
}