How do I retrace my steps after a wrong move?

This is a discussion on How do I retrace my steps after a wrong move? within the C++ Programming forums, part of the General Programming Boards category; ...it's the same program i've been trying to finish for weeks now. I still can't get it to work properly. ...

  1. #1
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    Mar 2003
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    Unhappy How do I retrace my steps after a wrong move?

    ...it's the same program i've been trying to finish for weeks now. I still can't get it to work properly.
    Can some loving person please help. I know this is qiute a bit of code to spiel....but this is just to help the kind one to undersand my algorithm.

    Please.....
    In the main I read the maze and print it( no problem with that). Then using the advance_maze function. Like so....

    Code:
    .
    int main()
    {
    	Move curr_move;
    	Curr_pos pos;
    	char Maze[40][40];
    	char filename[12];
    	int rows = 0;
    	int columns = 0;
    	MOVEDEQUE A;
    		
    	
    	cout<< "Please enter the name of the maze file you want to read, or (q) to quit.\n" << endl;
    	cout<< "(a) maze1.txt\n(b) maze2.txt\n(c) maze3.txt\n"<< endl;
    	cin.getline (filename, 10);
    	if (filename[0] == 'q')
    	{
    		return 0;
    	}
    	Read_file (Maze, &columns, &rows, pos, filename);
    	curr_move.maze_col = pos.col;
    	curr_move.maze_row = pos.row;
    	curr_move.move_number = 3;
    	Print_m_array (Maze, rows, columns);
    	A.push_back(curr_move);
    	
    	advance_maze(curr_move, A, Maze, &rows, &columns);
    	Print_m_array (Maze, rows, columns);
    	
    	
    	return 0;	
    }
    .

    This is the part that is not working well.

    Code:
    .
    
    void advance_maze( Move &move, MOVEDEQUE &M, char m_array[][40], int *columns, int *rows)
    {
    	
    	int n;
    	n = move.move_number;
    	int nxtrow = 0;
    	int nxtcol = 0;
    	bool blocked;
    	bool foundnxt_step;
    	//Move current_m;
    	
    	//M.push_back(move);
    	blocked = false;
    	foundnxt_step = false;
    	while (!M.empty())
    	{
    		//	move = M.back();
    		//  M.pop_back();
    		//M.push_back(move);
    		
    		if (m_array[move.maze_row][move.maze_col] == '0' || m_array[move.maze_row][move.maze_col] == 'E' )
    		{
    			m_array[move.maze_row][move.maze_col] = '*';
    			
    			nxtrow = move.maze_row + position[n].vertical;
    			nxtcol = move.maze_col + position[n].horizontal;
    			move.maze_row = nxtrow;
    			move.maze_col = nxtcol;
    			
    			for (; n<4;n++)
    			{
    				
    				if ( nxtrow < *rows && nxtcol < *columns && m_array[move.maze_row][move.maze_col] == '0')
    				{
    					
    					M.push_back(move);
    					//	m_array[move.maze_row][move.maze_col] = '*';
    					//move.maze_row = nxtrow;
    					//move.maze_col = nxtcol;
    					foundnxt_step = true;
    					for (; n<4 && foundnxt_step == true; )
    					{
    						m_array[move.maze_row][move.maze_col] = '*';
    						nxtrow = move.maze_row + position[n].vertical;
    						nxtcol = move.maze_col + position[n].horizontal;
    						move.maze_row = nxtrow;
    						move.maze_col = nxtcol;
    						
    						if(m_array[move.maze_row][move.maze_col] != '0')
    						{
    							foundnxt_step = false;
    							move = M.back();
    							//m_array[move.maze_row][move.maze_col] = '0';
    							n = 0;
    						}
    						else
    						{
    							M.push_back(move);
    							//m_array[move.maze_row][move.maze_col] = '*';
    						}
    					}
    					
    					
    					
    					/*if (m_array[nxtrow][nxtcol] != '0')
    					{
    					foundnxt_step = false;
    					n=0;
    				}*/
    					
    				}
    				else if (m_array[move.maze_row][move.maze_col] == 'X')
    				{
    					M.pop_back();
    					cout<< " Yah!!! Maze solved!! "<< endl;
    					break;
    				}
    				if (foundnxt_step == false)
    				{
    					//M.pop_back
    					for (; n<4 && foundnxt_step == false; n++ )
    					{
    						//n++;
    						nxtrow = move.maze_row + position[n].vertical;
    						nxtcol = move.maze_col + position[n].horizontal;
    						move.maze_row = nxtrow;  
    						move.maze_col = nxtcol;   
    						
    						
    						if (m_array[move.maze_row][move.maze_col] == '0')/// Why does it complain about a stack
    						{                                                    /// overflow here?
    							foundnxt_step = true;
    							///M.push_back(move);
    							//n =0;
    						}
    					}
    					if (n>3 && m_array[nxtrow][nxtcol] != '0')
    					{
    						blocked = true;
    						M.pop_back();
    						move =  M.back();
    					}
    					
    				}
    				
    			}
    		}
    		
    	}
    	
    	if (M.empty() && blocked == true)
    	{
    		cout<< "Awwww... sorry, this maze cannot be solved."<< endl;
    	}
    }
    .

    Thanks for taking a peek.!Really i'm very grateful.

  2. #2
    Grammar Police HybridM's Avatar
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    Jan 2003
    Posts
    355
    Although my programs aren't very big yet, what i do is compile after most things i do, that way i know if something starts working improperly, or it doesn't compile, that it's just a few ctrl+z presses away.

    I don't think i'm going to read all that code. :-/ Someone else more knowledgable will help i'm sure.
    Thor's self help tip:
    Maybe a neighbor is tossing leaf clippings on your lawn, looking at your woman, or harboring desires regarding your longboat. You enslave his children, set his house on fire. He shall not bother you again.

    OS: Windows XP
    Compiler: MSVC

  3. #3
    Cheesy Poofs! PJYelton's Avatar
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    Location
    Boulder
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    I would like to help, but unfortunately the code is rather hard to follow without more information. Is there anyway you can go back and comment everything then repost the code? Otherwise it'll take forever trying to guess what logic and methods you are using which will make it impossible to fix your error.

  4. #4
    Registered User major_small's Avatar
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    Re: How do I retrace my steps after a wrong move?

    Code:
    for (; n<4 && foundnxt_step == false; n++ )
    {
         //n++;
         nxtrow = move.maze_row + position[n].vertical;
         nxtcol = move.maze_col + position[n].horizontal;
         move.maze_row = nxtrow;  
         move.maze_col = nxtcol;   
    						
    						
         if (m_array[move.maze_row][move.maze_col] == '0')/// Why does it complain about a stack
         {					              /// overflow here?
              foundnxt_step = true;
              ///M.push_back(move);
              //n =0;
         }
    }
    the bolded code increases move.maze exponentially... the code I would have used is as follows (in place of bold code):
    Code:
    move.maze_row+=position[n].vertical;
    mxtrow=move.maze_row
    Last edited by major_small; 05-15-2003 at 11:23 AM.

  5. #5
    i want wookie cookies the Wookie's Avatar
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    Code:
    if (m_array[move.maze_row][move.maze_col] == '0')/// Why does it complain about a stack
         {					              /// overflow here?
              foundnxt_step = true;
              ///M.push_back(move);
              //n =0;
         }
    it maybe giving that error because the bounds of an array are n-1, so you may just have to subtract 1 from both the row and column count

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