图的深度优先搜索和广度优先搜索算法、最小生成树两种算法 --C++实现

#ifndef _GRAPH_H
#define _GRAPH_H

#include <iostream>
#include <string.h>
#include <assert.h>
#include <queue>
using namespace::std;

#define MAX_COST 0x7FFFFFFF   //花费无限大设为整型最大值

///////////////////////////////////////////////////////////////////////////////////////////
//通用图结构
template <typename T, typename E>
class graph{
public:
	bool is_empty()const;
	bool is_full()const;
	
	int get_numvertices()const;    //当前顶点数
	int get_numedges()const;       //当前边数
public:
	virtual bool insert_vertex(const T&) = 0;            //插入顶点
	virtual bool insert_edge(const T&, const T&, E) = 0;    //插入边

	virtual int get_firstneighbor(const T&)const = 0;    //得到第一个邻接顶点
	virtual int get_nextneighbor(const T&, const T&)const = 0;    //某邻接顶点的下一个邻接顶点
	
	virtual void print_graph()const = 0;
	virtual int get_vertex_index(const T&)const = 0;     //得到顶点序号

	virtual void depth_first(const T&) = 0;
	virtual void broad_first(const T&) = 0;

	virtual void min_spantree_kruskal() = 0;
	virtual void min_spantree_prim(const T&) = 0;
protected:
	static const int VERTICES_DEFAULT_SIZE = 10;         //默认图顶点数
	int max_vertices;
	int num_vertices;
	int num_edges;
};

template <typename T, typename E>
bool graph<T, E>::is_empty()const
{
	return num_edges == 0;
}

template <typename T, typename E>
bool graph<T, E>::is_full()const
{
	return num_vertices >= max_vertices 
		   || num_edges >= max_vertices*(max_vertices-1)/2;    //判满，分为顶点满和边满
}

template <typename T, typename E>
int graph<T, E>::get_numvertices()const
{
	return num_vertices;
}

template <typename T, typename E>
int graph<T, E>::get_numedges()const
{
	return num_edges;
}

///////////////////////////////////////////////////////////////////////////////////////////

#define VERTICES_DEFAULT_SIZE graph<T, E>::VERTICES_DEFAULT_SIZE
#define num_vertices          graph<T, E>::num_vertices   
#define num_edges             graph<T, E>::num_edges
#define max_vertices          graph<T, E>::max_vertices         

///////////////////////////////////////////////////////////////////////////////////////////

#endif /*graph.h*/

#pragma once

#include "graph.h"

//图的邻接矩阵表示法
template <typename T, typename E>
class graph_mtx : public graph<T, E>{
public:
	graph_mtx(int);                   
	~graph_mtx();                             
public:
	bool insert_vertex(const T&);
	bool insert_edge(const T&, const T&, E);  

	int get_firstneighbor(const T&)const;
	int get_nextneighbor(const T&, const T&)const;
	
	int get_vertex_index(const T&)const;
	T& get_vertex_symbol(const int)const;
	void print_graph()const;

	void depth_first(const T&);
	void broad_first(const T&);

	void min_spantree_kruskal();
	void min_spantree_prim(const T&);
protected:
	void depth_first(const T&, bool *);
private:
	T* vertices_list;                        //顶点线性表
	E **edge;                              //内部矩阵
};

template <typename T, typename E>
graph_mtx<T, E>::graph_mtx(int sz = VERTICES_DEFAULT_SIZE)
{
	max_vertices = sz > VERTICES_DEFAULT_SIZE ? sz 
									: VERTICES_DEFAULT_SIZE;
	vertices_list = new T[max_vertices];

	edge = new int*[max_vertices];                    //动态申请二维数组
	for(int i=0; i<max_vertices; ++i){	
		edge[i] = new int[max_vertices];
	}

	for(int i=0; i<max_vertices; ++i)
		for(int j=0; j<max_vertices; ++j){
			if(i != j)
				edge[i][j] = MAX_COST;
			else
				edge[i][j] = 0;
		}

	num_vertices = 0;
	num_edges = 0;
}

template <typename T, typename E>
graph_mtx<T, E>::~graph_mtx()
{
	for(int i=0; i<max_vertices; ++i)
		delete []edge[i];                     //分别析构，再总析构
	
	delete edge;
	delete []vertices_list;
}

template <typename T, typename E>
bool graph_mtx<T, E>::insert_vertex(const T& vert)
{
	if(this->is_full())                       //派生类函数调用父类函数，用this或加作用域
		return false;
	vertices_list[num_vertices++] = vert;
	return true;
}

template <typename T, typename E>
bool graph_mtx<T, E>::insert_edge(const T& vert1, const T& vert2, E cost = MAX_COST)//由于权值存在默认值，get_neighbor的操作需判断是否等于MAX_COST，否则不能正常取得邻接顶点
{
	if(this->is_full())                       //判满
		return false;

	int index_v1 = get_vertex_index(vert1);   //得到顶点序号
	int index_v2 = get_vertex_index(vert2);

	if(index_v1 == -1 || index_v2 == -1 )
		return false;
	
	edge[index_v1][index_v2] = edge[index_v2][index_v1] = cost;    //无向图
	++num_edges;	
	
	return true;
}

template <typename T, typename E>
int graph_mtx<T, E>::get_firstneighbor(const T& vert)const
{
	int index = get_vertex_index(vert);

	if(index != -1){
		for(int i=0; i<num_vertices; ++i){
			if(edge[index][i] != 0 && edge[index][i] != MAX_COST)  //加上判断MAX_COST
				return i;
		}
	}
	return -1;
}

template <typename T, typename E>
int graph_mtx<T, E>::get_nextneighbor(const T& vert1, const T& vert2)const
{
	int index_v1 = get_vertex_index(vert1);
	int index_v2 = get_vertex_index(vert2);

	if(index_v1 != -1 && index_v2 != -1){
		for(int i=index_v2+1; i<num_vertices; ++i){
			if(edge[index_v1][i] != 0 && edge[index_v1][i] != MAX_COST)
				return i;
		}
	}
	return -1;
}

template <typename T, typename E>
int graph_mtx<T, E>::get_vertex_index(const T& vert)const
{
	for(int i=0; i<num_vertices; ++i){
		if(vertices_list[i] == vert)
			return i;
	}
	return -1;
}

template <typename T, typename E>
T& graph_mtx<T, E>::get_vertex_symbol(const int index)const
{
	assert(index >= 0 && index < this->get_numvertices());
	//assert(index >= 0 && index < num_vertices); //error，由于num_vertices本身是我们用宏替换父类该元素，在这里使用会出现双重宏
	return vertices_list[index];
}

template <typename T, typename E>
void graph_mtx<T, E>::print_graph()const
{
	if(this->is_empty()){
		cout << "nil graph" << endl;                      //空图输出nil
		return;
	}
	
	for(int i=0; i<num_vertices; ++i){
		cout << vertices_list[i] << "  ";
	}
	cout << endl;

	for(int i=0; i<num_vertices; ++i){
		for(int j=0; j<num_vertices; ++j){
			if(edge[i][j] != MAX_COST)
				cout << edge[i][j] << "  ";
			else
				cout << '@' << "  ";        //若权值无限大，以@代替
		}
		cout << vertices_list[i] << endl;
	}
}


template <typename T, typename E>
void graph_mtx<T, E>::depth_first(const T& vert)   //深度优先，认准一条路往死走，无路可走再回退
{
	int num = this->get_numvertices();
	bool *visited = new bool[num];

	memset(visited, 0, sizeof(bool)*num);          //首先全部赋值为假，遍历过后为真，防止图死循环
	depth_first(vert, visited); 
	cout << "end.";
	
	delete []visited;
}

template <typename T, typename E>
void graph_mtx<T, E>::depth_first(const T& vert, bool *visited)
{
	cout << vert << "-->";

	int index = get_vertex_index(vert);
	visited[index] = true;

	int neighbor_index = get_firstneighbor(vert);
	while(neighbor_index != -1){
		if(!visited[neighbor_index])
			depth_first(get_vertex_symbol(neighbor_index), visited);   //递归
		
		neighbor_index = get_nextneighbor(vert,
								get_vertex_symbol(neighbor_index));
	}
}

template <typename T, typename E>
void graph_mtx<T, E>::broad_first(const T& vert)
{
	int num = this->get_numvertices();
	bool *visited = new bool[num];
	int index = get_vertex_index(vert);
	assert(index != -1);
	
	memset(visited, 0, sizeof(bool)*num);
	
	queue<int> que;                    //通过队列，将元素以次入队
	que.push(index);

	cout << vert << "-->";
	visited[index] = true;

	while(!que.empty()){
		int index_tmp = que.front();
		que.pop();

		int neighbor_index = get_firstneighbor(get_vertex_symbol(index_tmp));
		while(neighbor_index != -1){
			if(!visited[neighbor_index]){
				cout << get_vertex_symbol(neighbor_index) << "-->";
				visited[neighbor_index] = true;                  //遍历过后为真，防止图死循环
				que.push(neighbor_index);
			}
			neighbor_index = get_nextneighbor(get_vertex_symbol(index_tmp),
											  get_vertex_symbol(neighbor_index));
		}
	}
	cout << "end.";
	
	delete []visited;
}

//////////////////////////////////////////////////////////////////
//min_spactree_kruskal
template <typename T, typename E>
struct _mst_edge{                  //最小生成树边的结构体,<begin, end>为一组边，cost为花费
	int begin;
	int end;
	E cost;
};

template <typename T, typename E>
int compare(const void* vp1, const void* vp2)  
{
	return (*(_mst_edge<T, E> *)vp1).cost - (*(_mst_edge<T, E> *)vp2).cost;
}

bool _is_same(int *father, int begin, int end)            //判断是否在同一张子图中
{
	while(father[begin] != begin)
		begin = father[begin];
	while(father[end] != end)
		end = father[end];        
	
	return begin == end;                       //以最后一个元素是否存在父子关系判断
}

void mark_same(int *father, int begin, int end)
{
	while(father[begin] != begin)
		begin = father[begin];
	while(father[end] != end)
		end = father[end];
	
	father[end] = begin;                    //让最后一个元素连接起来，使它们成为同一子图的元素
}

template <typename T, typename E>
void graph_mtx<T, E>::min_spantree_kruskal()
{
	int num = this->get_numvertices();
	_mst_edge<T, E> *mst_edge = new _mst_edge<T, E>[num*(num-1)/2];

	int k = 0;
	for(int i=0; i<num; ++i)
		for(int j=i+1; j<num; ++j){       //建立有效边结构体数组，从i+1开始，直接统计矩阵1/2边数，不会产生重复
			if(edge[i][j] != MAX_COST){
				mst_edge[k].begin = i;
				mst_edge[k].end = j;
				mst_edge[k].cost = edge[i][j];
				++k;
			}
		}

	qsort(mst_edge, k, sizeof(_mst_edge<T, E>), compare<T, E>);   //调用快速排序函数

	int *father = new int[num];          //初始化使所有元素的父指向自己
	for(int i=0; i<num; ++i)
		father[i] = i;
	
	for(int i=0; i<num; ++i)
		if(!_is_same(father, mst_edge[i].begin, mst_edge[i].end)){  //判断是否在同一张子图中
			cout << get_vertex_symbol(mst_edge[i].begin) << "-->" 
								<< get_vertex_symbol(mst_edge[i].end)
								<< ":"  << mst_edge[i].cost << endl;
			mark_same(father, mst_edge[i].begin, mst_edge[i].end);   //加入后做标记
		}
		
	delete []father;
	delete []mst_edge;
}

//////////////////////////////////////////////////////////////////
//min_spantree_prim

template <typename T, typename E>
void graph_mtx<T, E>::min_spantree_prim(const T& vert)
{
	int num = this->get_numvertices();
	int *lowcost = new int[num];   //最小花费数组
	int *mst = new int[num];       //起始位置数组 <mst[i], i> 为一组边，起始为mst[i]

	int index = get_vertex_index(vert);
	assert(index != -1);

	for(int i=0; i<num; ++i){      //初始化使每个元素默认花费是以起始边为vert作为基准，所以mst[i]对应下标即为vert的下标index
		if(edge[index][i] != 0){
			lowcost[i] = edge[index][i];
			mst[i] = index;
		}
		else
			lowcost[i] = 0;
	}
	
	for(int i=0; i<num-1; ++i){     //循化，num个元素共有num-1条边
		int min = MAX_COST;
		int min_index = -1;
		
		for(int j=0; j<num; ++j){
			if(lowcost[j] != 0 && lowcost[j] < min){    //找出最小花费
				min = lowcost[j];
				min_index = j;
			}
		}

		cout << get_vertex_symbol(mst[min_index]) << "-->" 
			 		<< get_vertex_symbol(min_index) << ":" << min << endl;

		lowcost[min_index] = 0;    //花费为0，相当于加入已生成树中
		
		for(int j=0; j<num; ++j){   //循环，如果某元素到新元素的花费比默认花费小，那么就更新它，
			int cost = edge[min_index][j];//下次再循环到上面找最小花费时，就可能找到更新的这个最小花费，这就相当于每次加入新元素后
			if(cost < lowcost[j]){          //其他顶点挑出与已生成树所有顶点的花费最小值，并更新
				lowcost[j] = cost;
				mst[j] = min_index;
			}
		}
	}
	
	delete []lowcost;
	delete []mst;
}