head.h

#include<iostream>
using namespace std;

#define MAX_VEX_NUM 20

class ArcNode //弧节点
{
public:
	ArcNode();
	int tailnode;
	ArcNode *next;
};

ArcNode::ArcNode()
{
	next = NULL;
}

class VexNode //顶点节点
{
public:
	VexNode();
	char name;
	int indegree;
	ArcNode *firstarc;
};

VexNode::VexNode()
{
	indegree = 0;
	firstarc = NULL;
}

class VexBox //顶点集合
{
public:
	VexBox();
	VexNode vexbox[MAX_VEX_NUM];
	int vexnum;
};

VexBox::VexBox()
{
	vexnum = 0;
}

class TPSort //拓扑排序类
{
public:
	void GetTPSquence(); //接口函数
private:
	void GetVex(); //得到顶点信息
	void GetArc(); //得到弧信息
	void TPSorting(); //拓扑排序
	VexBox v;
};

void TPSort::GetTPSquence() //接口函数
{
	GetVex(); //得到顶点信息
	GetArc(); //得到弧信息
	TPSorting(); //拓扑排序
}

void TPSort::GetVex() //得到顶点信息
{
	cout << "Please Input The Name Of Each Vertex :" << endl << endl;
	char name;
	while (cin >> name)
	{
		v.vexbox[v.vexnum++].name = name;
	}
	cin.clear();
}

void TPSort::GetArc() //得到弧信息
{
	cout << "Please Input The Tail And Head Of Each Arc :" << endl << endl;
	int vex1, vex2;
	ArcNode *newnode, *p;
	while (cin >> vex1 >> vex2)
	{
		newnode = new ArcNode;
		newnode->tailnode = vex2;
		v.vexbox[vex2].indegree++;
		if ((p = v.vexbox[vex1].firstarc) == NULL)
		{
			v.vexbox[vex1].firstarc = newnode;
		}
		else
		{
			while (p->next != NULL)
				p = p->next;
			p->next = newnode;
		}
	}
	cin.clear();
}

void TPSort::TPSorting() //拓扑排序
{
	int count = 0;
	bool find = false;
	ArcNode *p;
	while (1)
	{
		for (int i = 0; i < v.vexnum; i++)
		{
			if (v.vexbox[i].indegree == 0) //删除入度为零
			{
				v.vexbox[i].indegree--;
				cout << v.vexbox[i].name << endl;
				find = true;
				count++;
				p = v.vexbox[i].firstarc;
				while (p != NULL) //相关顶点的入度减一
				{
					v.vexbox[p->tailnode].indegree--;
					p = p->next;
				}
				break;
			} //if
		} //for
		if (find == false)
			break;
		else
			find = false;
	} //while
	if (count == v.vexnum)
		cout << "This Is A Acycline Graph :" << endl << endl; //无环图
	else
		cout << "This Is A Cycling Graph :" << endl << endl; //有环
} //TPSorting

main.cpp

#include"head.h"
 
int main()
{
	TPSort tp;
	tp.GetTPSquence();
	system("pause");
}