Error: infinite loop in my code(Depth First Search)
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Thread: Error: infinite loop in my code(Depth First Search)

  1. #1
    Join Date
    Aug 2012
    Posts
    28

    Error: infinite loop in my code(Depth First Search)

    I code the algorithm Depth First Search, but it infinite loop, what did i wrong?
    Code:
    #include <iostream>
    #include <vector>
    using std::cout;
    using std::cin;
    using std::endl;
    const int maxx = 20;
    void Read_input_from_user(bool grid[][maxx], int vertices)
    {
        int u, v;
        for(int x = 0; x < vertices; ++x)
        {
            cout << "Enter u : \t"; 
            cin >> u;
            u--;
            cout << "Enter v : \t";
            cin >> v;
            v--;
            grid[u][v] = true;
            grid[v][u] = true;
            cout << "---------------------\n";
        }
    } 
    
    void Depth_first_search(bool grid[][maxx], std::vector<int> &trace, 
                            int nodes, int u) 
    {
    	
    	
        for(int v = 0; v < nodes; ++v)
        {
            if((grid[u][v] == true) && trace[v] == 0)
            {
    			
                trace[v] = u;
    			
                //recursive step
                Depth_first_search(grid, trace, nodes, v);
    			
            }
        }
    }
    
    void Trace_result(std::vector<int> &trace, int start, int end, int nodes) 
    {   
        cout << "From _nodes" << start + 1 << " you can visit :\n";
        for(int v = 0; v < nodes; ++v)
        {
            if(trace[v] != 0)
            {
                cout << " _nodes : " << v + 1 << " , ";
            }
        }
    
        cout << "\n--------------------------------------------\n";
        cout << "The path from " << start + 1 << " to " << end + 1 << '\n';
        
        if(trace[end] == 0){
            cout << "Unavailable.! to go to from " << end + 1 
                 << " to -> " << start + 1 << '\n';
        }
        else{
            while(end != start)
            {
                cout << end + 1 << "<-";
                end = trace[end];
            }
            cout << start + 1 << endl;
        } 
    }
    
    int main()
    {
        bool grid[maxx][maxx] = { false };
        std::vector<int> trace(maxx, 0);
        int nodes, vertices;
        cout << "Please input the number of Node : \n";
        cin >> nodes;
        cout << "Please input the number of Vertices : \n";
        cin >> vertices;
    
        //Set value for all vertices.
        Read_input_from_user(grid, vertices); 
    
        //Read the necessary path
        int starting_position, finishing_position;
        cout << "Please Input the Starting Node : \n";
        cin >> starting_position;
        cout << "Please Input the Finishing Node : \n";
        cin >> finishing_position;
        //Decrease to fit with index of C++ start from 0->size-1
        starting_position--;
        finishing_position--; 
    
        Depth_first_search(grid, trace, nodes, starting_position); 
        Trace_result(trace, starting_position, finishing_position, nodes);
    	system("pause");
        return 0;
    }
    I'm wrong in: Depth_first_search, is't it?

  2. #2
    GCDEF is offline Elite Member Power Poster
    Join Date
    Nov 2003
    Posts
    12,091

    Re: Error: infinite loop in my code(Depth First Search)

    Have you tried stepping through your code in the debugger?

  3. #3
    Join Date
    Aug 2012
    Posts
    28

    Re: Error: infinite loop in my code(Depth First Search)

    >"< i don't know how to use degger in C#, i'm begginer

  4. #4
    GCDEF is offline Elite Member Power Poster
    Join Date
    Nov 2003
    Posts
    12,091

    Re: Error: infinite loop in my code(Depth First Search)

    This is a C++ forum, not C#. You need to learn to use the debugger. It's not optional, and it's the first thing any of us here would do to figure out what was wrong with your code.

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