Seite 5: Listing

Inhaltsverzeichnis

Listing: Task-paralleler Sudoku-Löser

void main()
{
/* Sudoku Bord aufsetzen */
#pragma omp parallel
  {
#pragma omp single
    {
#pragma omp taskgroup
       {
          solve_parallel(0, 0, sudoku);
       }
    }
  } // end omp parallel
}


void solve_parallel(int x, int y, CSudokuBoard* sudoku, CSudokuBoard* 
       

& solution)
{
  if (x == sudoku->getFieldSize()) {      // end of line
    y++;   x = 0;
    if(y == sudoku->getFieldSize())     // end
      return true;
  }   
  
  if (sudoku->get(y, x) > 0) {            // field already set
    return solve_parallel(x+1, y, sudoku); // tackle next field
  }
        
  for (int i = 1; i <= sudoku->getFieldSize(); i++) { // try all numbers
    if (!sudoku->check(x, y, i)) {                    
#pragma omp task firstprivate(i,x,y,sudoku)
      {
        CSudokuBoard* new_sudoku = new CSudokuBoard(*sudoku);
        new_sudoku->set(y, x, i); // if number fits, set it
        if (solve_parallel(x+1, y, new_sudoku)) { // tackle next field
          // remember Sudoku board and stop parallel execution
#pragma omp critical 
          if (!solution) {
            solution = new_sudoku;
#pragma omp cancel taskgroup
          }
        }
        delete new_sudoku;
      }
    }
  }
#pragma omp taskwait
    
  sudoku->set(y, x, 0);               // no solution found, reset field
}


(ane)