[英]BFS and DFS of a graph in C++
我一直在尝试对图表进行BFS和DFS处理。 我已经尝试了所有方法,但仍然无法弄清楚我的算法出了什么问题。 请帮我解决一下这个。
我将带有的顶点作为向量发送,该向量指向图的顶点指向bfs和bfs,以便遍历它并寻找正确的值。 我对此并不陌生,尝试解决它时遇到很多问题。 如果有人可以浏览我的代码,看看我的算法在哪里出错,那将是很好的。 我希望能有新的发现。
它确实显示了输出,但是是错误的!
这是我的图表输入值:: 5 1、5 2、5 3、1 4、1 6
这里1是5的边缘,2是5的边缘,3是5的边缘,依此类推....
这是我得到的输出:对于BFS:5、1、2、3、4、6
对于DFS:5、4、3、2、1、5
这是我的算法:
#ifndef SORT_HPP
#define SORT_HPP
#include <string>
#include <iostream>
#include <fstream>
#include <sstream>
#include <list>
#include <vector>
#include <stack>
#include <algorithm>
#include "clsVertex.hpp"
#include "clsFileGraph.hpp"
#include "clsGraph.hpp";
class bfs : public clsGraph{
int vert;
public:
bfs(int s, vector<clsVertex*> verticies); //prints BFS traversal from a given source
};
class dfs: public clsGraph{
int vert;
list<int> adj;
public:
dfs(int s, vector<clsVertex*> verticies); //prints DFS traversal from a given source
};
bfs::bfs(int s, vector<clsVertex*> verticies){
bool *visited = new bool[verticies.size()]; //creates a new boolean array of the size of the graph
for (int i = 0; i < verticies.size(); i++){ //loops till the end of the graph
int x = verticies[i]->ID; //gets the value of each vertex
//cout << "The val: " << verticies[i]->ID << endl;
visited[x] = false; //marks that vertex as unvisited i.e: visited = false
}
list<int> queue; //creates a queue
visited[s] = true; //marks the starting point as visited
queue.push_back(s); //adds the starting point to the queue
cout << endl << "The breath first sort is as follows:-" << endl << endl;
while (queue.size() != 0){ //loops until the size of the queue is 0
for (int i = 0; i < verticies.size(); i++){ //loops
int y = verticies[i]->edges.size();
for (int j = 0; j < y; j++){
int z = verticies[i]->edges[j]->ID;
if (visited[z]== false){
visited[z] = true;
queue.push_back(z);
}
}
}
cout << s << ",";
queue.pop_front();
if (queue.size() == 0)
goto here;
s = queue.front();
}
here:
cout << ID << " " << graphType << endl;
for (int i = 0; i < verticies.size(); i++){
cout << verticies[i]->ID << "->";
for (int j = 0; j < verticies[i]->edges.size(); j++){
cout << verticies[i]->edges[j]->ID << endl;
}
}
cout << endl << endl << "Done" << endl << endl;
}
// DFS traversal of the vertices reachable from v. It uses recursive DFSUtil()
dfs::dfs(int s, vector<clsVertex*> verticies)
{
// Mark all the vertices as not visited
bool *visited = new bool[verticies.size()]; //creates a new boolean array of the size of the graph
for (int i = 0; i < verticies.size(); i++){ //loops till the end of the graph
int x = verticies[i]->ID; //gets the value of each vertex
//cout << "The val: " << verticies[i]->ID << endl;
visited[x] = false; //marks that vertex as unvisited i.e: visited = false
}
stack <int> depth;
visited[s] = true;
depth.push(s);
//cout << s << ",";
while (depth.size() != 0){ //loops until the size of the queue is 0
for (int i = 0; i < verticies.size(); i++){ //loops
int y = verticies[i]->edges.size();
for (int j = 0; j < y; j++){
int z = verticies[i]->edges[j]->ID;
if (visited[z] == false){
visited[z] = true;
depth.push(z);
}
}
}
cout << s << ",";
depth.pop();
if (depth.size() == 0)
goto there;
s = depth.top();
}
there:
cout << "done";
}
#endif
您的BFS方法无法正常工作,因为您要向队列中添加的所有顶点均乱序。 您应该将while ( queue.size > 0 )
循环的内部替换为:
s = queue.pop_front();
for ( int i = 0; i < vertices[s]->edges.size(); i++ ) {
int tmp = vertices[s]->edges[i]->ID;
if ( !visited[tmp] ) {
visited[tmp] = true;
queue.push_back(tmp);
}
}
cout << s << " ";
目前,您添加了顶点1的邻居,然后添加了顶点2的邻居,甚至没有引用您假定的起点s。 您只需要添加当前队列顶部哪个顶点的邻居即可。
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