【数据结构】有向图邻接表的构建（C++）

数据结构里面的一道基础题，分享下自己的写法，验证可跑。     

#include<iostream>
#include<string>
const int MAX = 20;
using namespace std;


struct ArcNode {			        //弧结点
	int adjvex = -1;		        //所指顶点位置
	ArcNode *nextarc = nullptr;		//下一条狐指针
	size_t info = 0;			//弧信息
};


struct VNode {				        //顶点
	string data = "0";
	ArcNode *firstarc = nullptr;		//第一条依附该顶点的弧的指针
};


struct Graph {				        //图结构
	VNode vertices[MAX];	                //全部顶点
	int vexnum, arcnum;		        //顶点数和弧数
	Graph(int m, int n) :vexnum(m), arcnum(n) {};
	Graph() :vexnum(0), arcnum(0) {};
};


int main()
{
	int vnum, anum, tempanum = 0;
	cout << "输入顶点数：";
	cin >> vnum;
	cout << "输入弧数：";
	cin >> anum;
	cout << "\n\n";
	Graph G(vnum, anum);
	for (int i = 0; i != vnum; ++i) {
		cout << "输入结点" << i << "的信息：";
		cin >> G.vertices[i].data;
		if (tempanum != anum)
			cout << "输入依靠此结点的弧的信息（输入-1以停止）：\n";
		else
			cout << "已输入所有弧的信息！\n";
		bool first = true;
		ArcNode *p, *temp;
		for (int j = 0; (j != anum) && (tempanum != vnum); ++j) {
			int pointto;
			cout << "输入弧" << tempanum << "所指向的顶点位置：";
			cin >> pointto;
			if (pointto == -1)	break;
			else {
				++tempanum;
				if (first == true) {
					first = false;
					G.vertices[i].firstarc = new ArcNode;
					G.vertices[i].firstarc->adjvex = pointto;
					p = G.vertices[i].firstarc;
				}
				else {
					temp = new ArcNode;
					temp->adjvex = pointto;
					p->nextarc = temp;
					p = temp;
				}
			}
		}
		cout << endl;
	}
	
	for (int i = 0; i != anum; ++i) {
		cout << "顶点" << i << ": |" << G.vertices[i].data << "|";
		if (G.vertices[i].firstarc) {
			cout << " -> " << G.vertices[i].firstarc->adjvex;
			auto pt = G.vertices[i].firstarc->nextarc;
			while (pt) {
				cout << " -> " << pt->adjvex;
				pt = pt->nextarc;
			}
			cout <<  "-> ^";
		}
		else
			cout << " -> ^";
		cout << endl;
	}
	return 0;
}

由于只是单纯构建基本的无权值有向图邻接表，里面的弧结构中弧信息未利用到。