maze while loop problem

Question

seacat123 0 Newbie Poster

15 Years Ago

i have written the code . the while loop works good for right and down only. when i=9 and j=5 then it do not execute further . iam trying to fix the problem but not successful.

#include <cstdlib>
#include <iostream>
#include <fstream>

using namespace std;


       //----------------------------------------------------Print maze
    void fnPrintMaze(int m,int n,int**a)
       {
         for (int i=0; i<=m-1; i++)
          {
          for (int j=0; j<=n-1; j++)
              {
               cout<<a[i][j];
               cout<<" ";
               }
          cout<<endl;  
          }    
       }

      //----------------------------------------------------Find Path

     void fnFindPath(int m,int n, int **a)
     {
         int i=0;
         int j=0;


         if(i==0 && j==0)
          a[i][j]=2;

       do{   

          if((i>=0 && j+1>=0 && i<=m-1 && j+1<=n-1 )&& a[i][j+1]==0)//right
          {j++;
                  a[i][j]=2;

          }


         else if((i+1>=0 && j>=0 && i+1<=m-1 && j<=n-1) && a[i+1][j]==0)//down
          {i++;
          a[i][j]=2;

          }


          else 
                   if((i>=0 && j-1>=0 && i<=m-1 && j-1<=n-1) && a[i][j-1]==0)    //left  
         {
          j--;
          a[i][j]=2;
          }

          else if((i-1>=0 && j>=0 && i-1<=m-1 && j<=n-1) && a[i-1][j]==0)  //up   
          {
           i--;
          a[i][j]=2;

          }
        /*  

          else 
          if((i-1>=0 && j>=0 && i-1<=m-1 && j<=n-1) && a[i-1][j]==2)  //revisit up   
          {

          a[i][j]=3;
          i--;
          }


           else if((i>=0 && j-1>=0 && i<=m-1 && j-1<=n-1) && a[i][j-1]==2)     //revisit left
          {

          a[i][j]=3;
          j--;
          }







      */
     else 
        //{
           if((i>=0 && j+1>=0 && i<=m-1 &&j+1<=n-1) && a[i][j+1]==2)
          {
                  a[i][j]=3;
                  j++;
          }

          else if((i+1>=0 && j>=0 && i+1<=m-1 &&j<=n-1) && a[i+1][j]==2)
          {
          a[i][j]=3;
          i++;
          }


          else if((i>=0 && j-1>=0 && i<=m-1 && j-1<=n-1) && a[i][j-1]==2)     
          {

          a[i][j]=3;
          j--;
          }



          else if((i-1>=0 && j>=0 && i-1<=m-1 && j<=n-1) && a[i-1][j]==2)
          {

          a[i][j]=3;
          i--;

          }




        //}
        }while( ( i!=m-1) &&( j!=n-1));
         //while( !( i==m-1 && j==n-1)); 

     }




int main(int argc, char *argv[]) //main programe
{
    int m, n;
    int **maze;

    fstream fin("maze.txt", ios::in);
    fin>>m;
    fin>>n;

    maze= new int*[m];                                    //defining rows

    for (int i=0; i<=m-1; i++)
          maze[i]=new int[n];                            //defining columns


    for (int i=0; i<=m-1; i++)                              //reading values from txt and putting in matrix
          for (int j=0; j<=n-1; j++)
              fin>>maze[i][j];



     fnPrintMaze(m,n,maze);

    //for (int i=0; i<=m-1; i++)
        // for (int j=0; j<=n-1; j++)

               fnFindPath( m,n, maze);      

cout<<endl;
    fnPrintMaze(m,n,maze);


    system("PAUSE");
    return EXIT_SUCCESS;
}

the matrix is

10 10
0 1 1 1 0 0 0 0 0 0
0 0 0 1 0 0 0 1 0 0
0 1 0 1 1 0 0 1 0 0
0 1 0 0 1 0 1 1 0 0
0 1 0 0 1 0 1 1 0 0
1 1 1 0 1 0 1 0 0 0
0 0 1 0 0 0 1 0 1 1
0 0 1 0 0 0 1 0 1 1
0 1 1 0 1 0 1 0 0 0
0 0 0 0 1 0 1 1 0 0

c++

Edited 11 Years Ago by Dani because: Formatting fixed

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Latest Post 15 Years Ago Latest Post by seacat123

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Dave Sinkula 2,398 long time no c

15 Years Ago

That's due to the if-else tree: right and down possibilities are checked first. Making up and left priorities higher, you might get this:

#include <cstdlib>
#include <iostream>
#include <fstream>

using namespace std;

//----------------------------------------------------Print maze
void fnPrintMaze(int m,int n,int**a)
{
   for ( int i=0; i<=m-1; i++ )
   {
      for ( int j=0; j<=n-1; j++ )
      {
         cout<<a[i][j];
         cout<<" ";
      }
      cout<<endl;
   }
}

//----------------------------------------------------Find Path
void fnFindPath(int m,int n, int **a)
{
   int i=0;
   int j=0;

   if ( i==0 && j==0 )
      a[i][j]=2;

   do
   {
      if ( (i>=0 && j-1>=0 && i<=m-1 && j-1<=n-1) && a[i][j-1]==0 ) //left
      {
         j--;
         a[i][j]=2;
      }
      else if ( (i-1>=0 && j>=0 && i-1<=m-1 && j<=n-1) && a[i-1][j]==0 ) //up
      {
         i--;
         a[i][j]=2;
      }
      else if ( (i>=0 && j+1>=0 && i<=m-1 && j+1<=n-1 )&& a[i][j+1]==0 )//right
      {
         j++;
         a[i][j]=2;
      }
      else if ( (i+1>=0 && j>=0 && i+1<=m-1 && j<=n-1) && a[i+1][j]==0 )//down
      {
         i++;
         a[i][j]=2;
      }
      else if ( (i>=0 && j+1>=0 && i<=m-1 &&j+1<=n-1) && a[i][j+1]==2 )
      {
         a[i][j]=3;
         j++;
      }
      else if ( (i+1>=0 && j>=0 && i+1<=m-1 &&j<=n-1) && a[i+1][j]==2 )
      {
         a[i][j]=3;
         i++;
      }
      else if ( (i>=0 && j-1>=0 && i<=m-1 && j-1<=n-1) && a[i][j-1]==2 )
      {
         a[i][j]=3;
         j--;
      }
      else if ( (i-1>=0 && j>=0 && i-1<=m-1 && j<=n-1) && a[i-1][j]==2 )
      {
         a[i][j]=3;
         i--;
      }
   }while ( ( i!=m-1) &&( j!=n-1) );
}

int main(int argc, char *argv[]) //main programe
{
   int m, n;
   int **maze;

   fstream fin("maze.txt", ios::in);
   fin>>m;
   fin>>n;

   maze= new int*[m]; //defining rows

   for ( int i=0; i<=m-1; i++ )
      maze[i]=new int[n]; //defining columns

   for ( int i=0; i<=m-1; i++ ) //reading values from txt and putting in matrix
      for ( int j=0; j<=n-1; j++ )
         fin>>maze[i][j];

   fnPrintMaze(m,n,maze);

   fnFindPath( m,n, maze);

   cout<<endl;
   fnPrintMaze(m,n,maze);

   return EXIT_SUCCESS;
}

/* my output
0 1 1 1 0 0 0 0 0 0 
0 0 0 1 0 0 0 1 0 0 
0 1 0 1 1 0 0 1 0 0 
0 1 0 0 1 0 1 1 0 0 
0 1 0 0 1 0 1 1 0 0 
1 1 1 0 1 0 1 0 0 0 
0 0 1 0 0 0 1 0 1 1 
0 0 1 0 0 0 1 0 1 1 
0 1 1 0 1 0 1 0 0 0 
0 0 0 0 1 0 1 1 0 0 

2 1 1 1 2 2 2 2 2 2 
2 2 2 1 2 2 0 1 0 0 
0 1 2 1 1 2 0 1 0 0 
0 1 2 2 1 2 1 1 0 0 
0 1 3 2 1 2 1 1 0 0 
1 1 1 2 1 2 1 0 0 0 
0 0 1 2 2 2 1 0 1 1 
0 0 1 0 0 0 1 0 1 1 
0 1 1 0 1 0 1 0 0 0 
0 0 0 0 1 0 1 1 0 0 
*/

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seacat123 0 Newbie Poster · Answer 1 · 2008-07-12T05:18:06+00:00

the answer of this question is to find path and your output is not showing path.

my logic is move right and down...then left and up...

third the two while conditions are not equal i was using while( ( i!=m-1) &&( j!=n-1));
and after i=9 and j=5 it was not working ..i still dont know why
but when i changed it to while( !( i==m-1 && j==n-1));
now its working and still iam stuck whats the difference... even in my current code if i comment my else part where i convert 2 into 3 ..the out displays only one matrix the orignal one not teh changed.. here is my new code that shows path but i have above questions in mind

#include <cstdlib>
#include <iostream>
#include <fstream>

using namespace std;


       //----------------------------------------------------Print maze
    void fnPrintMaze(int m,int n,int**a)
       {
         for (int i=0; i<=m-1; i++)
          {
          for (int j=0; j<=n-1; j++)
              {
               cout<<a[i][j];
               cout<<" ";
               }
          cout<<endl;  
          }    
       }

      //----------------------------------------------------Find Path

     void fnFindPath(int m,int n, int **a)
     {
         int i=0;
         int j=0;


         if(i==0 && j==0)
          a[i][j]=2;

       do{   
        //cout<< i<<endl;
          if((i>=0 && j+1>=0 && i<=m-1 && j+1<=n-1 )&& a[i][j+1]==0)//right
          {j++;
                  a[i][j]=2;

          }


         else if((i+1>=0 && j>=0 && i+1<=m-1 && j<=n-1) && a[i+1][j]==0)//down
          {i++;
          a[i][j]=2;

          }


          else 
                   if((i>=0 && j-1>=0 && i<=m-1 && j-1<=n-1) && a[i][j-1]==0)    //left  
         {
          j--;
          a[i][j]=2;

          }

          else if((i-1>=0 && j>=0 && i-1<=m-1 && j<=n-1) && a[i-1][j]==0)  //up   
          {
           i--;
          a[i][j]=2;

          } 


    //if i comment the all code written below my matrix dont appear why?     


     else 

           if((i>=0 && j+1>=0 && i<=m-1 &&j+1<=n-1) && a[i][j+1]==2)   //right
          {
                  a[i][j]=3;
                  j++;
          }

          else if((i+1>=0 && j>=0 && i+1<=m-1 &&j<=n-1) && a[i+1][j]==2)// down
          {
          a[i][j]=3;
          i++;
          }


          else if((i>=0 && j-1>=0 && i<=m-1 && j-1<=n-1) && a[i][j-1]==2)     //left
          {

          a[i][j]=3;
          j--;
          }



          else if((i-1>=0 && j>=0 && i-1<=m-1 && j<=n-1) && a[i-1][j]==2)// up
          {

          a[i][j]=3;
          i--;

          }



   cout<< i<<" "<<j <<endl;

        }//while( ( i!=m-1) &&( j!=n-1));
        while( !( i==m-1 && j==n-1)); 

     }




int main(int argc, char *argv[])
{
    int m, n;
    int **maze;

    fstream fin("maze.txt", ios::in);
    fin>>m;
    fin>>n;

    maze= new int*[m];                                    //defining rows

    for (int i=0; i<=m-1; i++)
          maze[i]=new int[n];                            //defining columns


    for (int i=0; i<=m-1; i++)                              //reading values from txt and putting in matrix
          for (int j=0; j<=n-1; j++)
              fin>>maze[i][j];



     fnPrintMaze(m,n,maze);

    //for (int i=0; i<=m-1; i++)
        // for (int j=0; j<=n-1; j++)

               fnFindPath( m,n, maze);      

cout<<endl;
    fnPrintMaze(m,n,maze);


    system("PAUSE");
    return EXIT_SUCCESS;
}

maze while loop problem

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