CS 201 - 10/16/14

   if ( var = 21 )    /* logic error - wrong symbol */

   if ( var == 21 )   /* use correct symbol */

   if ( 21  = var )   /* syntax error */

   if ( 21 == var )   /* using correct symbol */

   if ( arr[x][y] = ' ' )  /* logic error - wrong symbol */


==============================

struct coordStack
  {
    int x;
    int y;
    struct coordStack* next;
  }


          struct coordStack* head = NULL;

          char maze[22][22];
          int atEnd = FALSE;
          int currX, currY;
          int endX, endY;

          for ( x = ....)
             for ( y = ...)
                maze [x][y] = '.';

          /* put * along border */

          /* read input and put * in blocked positions */
     
/* Depth First Search */
          currX = 1;
          currY = 1;

          push (&head, currX, currY);
          maze[currX][currY] = 'v';

         
         while ( (isEmpty (head) == FALSE) &&
                 (atEnd == FALSE) )
            {
              currX = topX (head);
              currY = topY (head);

              if ( currX == endX && currY == endY )
                 {
                  atEnd = TRUE;
                  break;
                 }
              else
                 { /* check position above current */
                   /* X coord move left to right */
                  if ( maze[currX][currY-1] == '.' )
                     {
                       push (&head, currX, currY-1);
                       maze[currX][currY-1] = 'v';
                     }
                  else if ( maze[currX][currY+1] == '.' )
                     {
                       push (&head, currX, currY+1);
                       maze[currX][currY+1] = '^';
                     }
               else if ( maze[currX-1][currY] == '.' )
                     {
                       push (&head, currX-1, currY);
                       maze[currX-1][currY] = '>';
                     }
               else if ( maze[currX+1][currY] == '.' )
                     {
                       push (&head, currX+1, currY);
                       maze[currX+1][currY] = '<';
                     }
               else 
                     { /* backtrack */
                       pop (&head);
                     }



          }




/* Breadth First Search */
          currX = 1;
          currY = 1;

          addToEnd(&head, currX, currY);
          maze[currX][currY] = 'v';

         
         while ( (isEmpty (head) == FALSE) &&
                 (atEnd == FALSE) )
            {
              currX = frontX (head);
              currY = frontY (head);
              removeFromFront (&head);

              if ( currX == endX && currY == endY )
                 {
                  atEnd = TRUE;
                  break;
                 }
              else
                 { /* check position above current */
                   /* X coord move left to right */
                  if ( maze[currX][currY-1] == '.' )
                     {
                       addToEnd(&head, currX, currY-1);
                       maze[currX][currY-1] = 'v';
                     }
                  if ( maze[currX][currY+1] == '.' )
                     {
                       addToEnd(&head, currX, currY+1);
                       maze[currX][currY+1] = '^';
                     }
                  if ( maze[currX-1][currY] == '.' )
                     {
                       addToEnd(&head, currX-1, currY);
                       maze[currX-1][currY] = '>';
                     }
                  if ( maze[currX+1][currY] == '.' )
                     {
                       addToEnd(&head, currX+1, currY);
                       maze[currX+1][currY] = '<';
                     }
              
          }