广度优先搜索BFS C++实现

//BFS，使用 邻接矩阵+队列 实现
#include <iostream>
#include <queue>

using namespace std;

#define MAX_VERTS 20

class Vertex
{
public:
	Vertex(char lab)
	{
		Label = lab;
		wasVisited = false;
	}
public:
	bool wasVisited;
	char Label;
};

class Graph
{
public:
	Graph();
	~Graph();
	void addVertex(char lab);
	void addEdge(int start, int end);
	void printMatrix();
	void showVertex(int v);
	void BFS();
private:
	Vertex* vertexList[MAX_VERTS];
	int nVerts;
	int adjMat[MAX_VERTS][MAX_VERTS];

	int getAdjUnvisitedVertex(int v);
};

Graph::Graph()
{
	nVerts = 0;
	for (int i = 0; i < MAX_VERTS; i++)
	{
		for (int j = 0; j < MAX_VERTS; j++)
		{
			adjMat[i][j] = 0;
		}
	}
}

Graph::~Graph()
{
	//delete[] vertexList;
}
//添加顶点
void Graph::addVertex(char lab)
{
	vertexList[nVerts++] = new Vertex(lab);
}
//添加边
void Graph::addEdge(int start, int end)
{
	adjMat[start][end] = 1;
	adjMat[end][start] = 1;
}

void Graph::printMatrix()
{
	for (int i = 0; i < nVerts; i++)
	{
		for (int j = 0; j < nVerts; j++)
		{
			cout << adjMat[i][j] << " ";
		}
		cout << endl;
	}
}
//显示顶点标签
void Graph::showVertex(int v)
{
	cout << vertexList[v]->Label << " ";
}

//获得相邻接未访问过的下一个顶点
int Graph::getAdjUnvisitedVertex(int v)
{
	for (int j = 0; j < nVerts; j++)
	{
		//邻接的并且没被访问过
		if ((adjMat[v][j] == 1) && (vertexList[j]->wasVisited == false))
			return j;
	}

	return -1;
}


void Graph::BFS()
{
	queue<int> gQueue;
	vertexList[0]->wasVisited = true;
	showVertex(0);
	gQueue.push(0);

	int vert1, vert2;
	while (gQueue.size() > 0)
	{
		vert1 = gQueue.front();
		gQueue.pop();
		vert2 = getAdjUnvisitedVertex(vert1);
		while (vert2 != -1)	//找到所有与vert1相邻接的顶点
		{
			vertexList[vert2]->wasVisited = true;
			showVertex(vert2);
			gQueue.push(vert2);	//将访问过的顶点放入队列
			vert2 = getAdjUnvisitedVertex(vert1);
		}
	}

	cout << endl;
	//为了下一次搜索再把wasVisited变成false
	for (int j = 0; j < nVerts; j++)
		vertexList[j]->wasVisited = false;
}

int main()
{
	Graph g;
	g.addVertex('A');
	g.addVertex('B');
	g.addVertex('C');
	g.addEdge(0, 1);
	g.addEdge(0, 2);

	g.printMatrix();

	g.BFS();

	system("pause");
	return 0;
}