Exemplo n.º 1
0
int
Munkres::step1(void) {
    const unsigned int rows = matrix.rows,
    columns = matrix.cols;
    
    for ( unsigned int row = 0 ; row < rows ; row++ ) {
        for ( unsigned int col = 0 ; col < columns ; col++ ) {
            if ( 0 == matrix(row, col) ) {
                bool isstarred = false;
                for ( unsigned int nrow = 0 ; nrow < rows ; nrow++ )
                    if ( STAR == mask_matrix(nrow,col) ) {
                        isstarred = true;
                        break;
                    }
                
                if ( !isstarred ) {
                    for ( unsigned int ncol = 0 ; ncol < columns ; ncol++ )
                        if ( STAR == mask_matrix(row, ncol) ) {
                            isstarred = true;
                            break;
                        }
                }
                
                if ( !isstarred ) {
                    mask_matrix(row,col) = STAR;
                }
            }
        }
    }
    
    return 2;
}
Exemplo n.º 2
0
int 
Munkres::step1(void) {
  for ( int row = 0 ; row < matrix.rows() ; row++ )
    for ( int col = 0 ; col < matrix.columns() ; col++ )
      if ( matrix(row,col) == 0 ) {
        bool isstarred = false;
        for ( int nrow = 0 ; nrow < matrix.rows() ; nrow++ )
          if ( mask_matrix(nrow,col) == STAR ) {
            isstarred = true;
            break;
          }

        if ( !isstarred ) {
          for ( int ncol = 0 ; ncol < matrix.columns() ; ncol++ )
            if ( mask_matrix(row,ncol) == STAR ) {
              isstarred = true;
              break;
            }
        }
              
        if ( !isstarred ) {
          mask_matrix(row,col) = STAR;
        }
      }

  return 2;
}
Exemplo n.º 3
0
int
Munkres::step3(void) {
    /*
     Main Zero Search
     
     1. Find an uncovered Z in the distance matrix and prime it. If no such zero exists, go to Step 5
     2. If No Z* exists in the row of the Z', go to Step 4.
     3. If a Z* exists, cover this row and uncover the column of the Z*. Return to Step 3.1 to find a new Z
     */
    if ( find_uncovered_in_matrix(0, saverow, savecol) ) {
        mask_matrix(saverow,savecol) = PRIME; // prime it.
    } else {
        return 5;
    }
    
    for ( unsigned int ncol = 0 ; ncol < matrix.cols ; ncol++ ) {
        if ( mask_matrix(saverow,ncol) == STAR ) {
            row_mask[saverow] = true; //cover this row and
            col_mask[ncol] = false; // uncover the column containing the starred zero
            return 3; // repeat
        }
    }
    
    return 4; // no starred zero in the row containing this primed zero
}
Exemplo n.º 4
0
int
Munkres::step2(void) {
    const unsigned int rows = matrix.rows,
    columns = matrix.cols;
    unsigned int covercount = 0;
    
    for ( unsigned int row = 0 ; row < rows ; row++ )
        for ( unsigned int col = 0 ; col < columns ; col++ )
            if ( STAR == mask_matrix(row, col) ) {
                col_mask[col] = true;
                covercount++;
            }
    
    if ( covercount >= minsize(matrix) ) {
        if(isDiag) {
            std::cout << "Final cover count: " << covercount << std::endl;
        }
        return 0;
    }
    
    if(isDiag) {
        std::cout << "Munkres matrix has " << covercount << " of " << minsize(matrix) << " Columns covered:" << std::endl;
        for ( unsigned int row = 0 ; row < rows ; row++ ) {
            for ( unsigned int col = 0 ; col < columns ; col++ ) {
                std::cout.width(4);
                std::cout << matrix(row, col) << ",";
            }
            std::cout << std::endl;
        }
        std::cout << std::endl;
    }
    
    
    return 3;
}
Exemplo n.º 5
0
int 
Munkres::step2(void) {
	int covercount = 0;
	for ( int row = 0 ; row < matrix.rows() ; row++ )
		for ( int col = 0 ; col < matrix.columns() ; col++ )
			if ( mask_matrix(row,col) == Z_STAR ) {
				col_mask[col] = true;
				covercount++;
			}
			
	int k = matrix.minsize();

	if ( covercount >= k ) {
#ifdef DEBUG
		std::cout << "Final cover count: " << covercount << std::endl;
#endif
		return 0;
	}

#ifdef DEBUG
	std::cout << "Munkres matrix has " << covercount << " of " << k << " Columns covered:" << std::endl;
	for ( int row = 0 ; row < matrix.rows() ; row++ ) {
		for ( int col = 0 ; col < matrix.columns() ; col++ ) {
			std::cout.width(8);
			std::cout << matrix(row,col) << ",";
		}
		std::cout << std::endl;
	}
	std::cout << std::endl;
#endif


	return 3;
}
Exemplo n.º 6
0
int 
Munkres::step2() {
  const size_t rows = matrix.rows(),
            columns = matrix.columns();
  size_t covercount = 0;

  for ( size_t row = 0 ; row < rows ; row++ )
    for ( size_t col = 0 ; col < columns ; col++ )
      if ( STAR == mask_matrix(row, col) ) {
        col_mask[col] = true;
        covercount++;
      }
      
  if ( covercount >= matrix.minsize() ) {
#ifdef DEBUG
    std::cout << "Final cover count: " << covercount << std::endl;
#endif
    return 0;
  }

#ifdef DEBUG
  std::cout << "Munkres matrix has " << covercount << " of " << matrix.minsize() << " Columns covered:" << std::endl;
  for ( size_t row = 0 ; row < rows ; row++ ) {
    for ( size_t col = 0 ; col < columns ; col++ ) {
      std::cout.width(8);
      std::cout << matrix(row, col) << ",";
    }
    std::cout << std::endl;
  }
  std::cout << std::endl;
#endif


  return 3;
}
/*!
	Main Zero Search

   1. Find an uncovered Z in the distance matrix and prime it. If no such zero exists, go to Step 5
   2. If No Z* exists in the row of the Z', go to Step 4.
   3. If a Z* exists, cover this row and uncover the column of the Z*. Return to Step 3.1 to find a new Z
*/
int Munkres::step3(void) 
{
	if ( find_uncovered_in_matrix(0, saverow, savecol) ) {
		mask_matrix(saverow,savecol) = Z_PRIME; // prime it.
	} else {
		return 5;
	}

	for ( unsigned ncol = 0 ; ncol < matrix.columns() ; ncol++ )
		if ( mask_matrix(saverow,ncol) == Z_STAR ) {
			row_mask[saverow] = true; //cover this row and
			col_mask[ncol] = false; // uncover the column containing the starred zero
			return 3; // repeat
		}

	return 4; // no starred zero in the row containing this primed zero
}
Exemplo n.º 8
0
int 
Munkres::step1() {
  const size_t rows = matrix.rows(),
            columns = matrix.columns();

  for ( size_t row = 0 ; row < rows ; row++ ) {
    for ( size_t col = 0 ; col < columns ; col++ ) {
      if ( 0 == matrix(row, col) ) {
        for ( size_t nrow = 0 ; nrow < row ; nrow++ )
          if ( STAR == mask_matrix(nrow,col) )
            goto next_column;

        mask_matrix(row,col) = STAR;
        goto next_row;
      }
      next_column:;
    }
    next_row:;
  }

  return 2;
}
int Munkres::step1(void) 
{
	for ( unsigned row = 0 ; row < matrix.rows() ; row++ )
		for ( unsigned col = 0 ; col < matrix.columns() ; col++ )
			if ( matrix(row,col) == 0 ) {
				bool isstarred = false;
				for ( unsigned nrow = 0 ; nrow < matrix.rows() ; nrow++ )
					if ( mask_matrix(nrow,col) == Z_STAR )
						isstarred = true;

				if ( !isstarred ) {
					for ( unsigned ncol = 0 ; ncol < matrix.columns() ; ncol++ )
						if ( mask_matrix(row,ncol) == Z_STAR )
							isstarred = true;
				}
							
				if ( !isstarred ) {
					mask_matrix(row,col) = Z_STAR;
				}
			}

	return 2;
}
Exemplo n.º 10
0
void 
Munkres::solve(Matrix<double> &m) {
  // Linear assignment problem solution
  // [modifies matrix in-place.]
  // matrix(row,col): row major format assumed.

  // Assignments are remaining 0 values
  // (extra 0 values are replaced with -1)
#ifdef DEBUG
  std::cout << "Munkres input matrix:" << std::endl;
  for ( int row = 0 ; row < m.rows() ; row++ ) {
    for ( int col = 0 ; col < m.columns() ; col++ ) {
      std::cout.width(8);
      std::cout << m(row,col) << ",";
    }
    std::cout << std::endl;
  }
  std::cout << std::endl;
#endif

  double highValue = 0;
  for ( int row = 0 ; row < m.rows() ; row++ ) {
    for ( int col = 0 ; col < m.columns() ; col++ ) {
      if ( m(row,col) != INFINITY && m(row,col) > highValue )
        highValue = m(row,col);
    }
  }
  highValue++;
  
  for ( int row = 0 ; row < m.rows() ; row++ )
    for ( int col = 0 ; col < m.columns() ; col++ )
      if ( m(row,col) == INFINITY )
        m(row,col) = highValue;

  bool notdone = true;
  int step = 1;

  this->matrix = m;
  // STAR == 1 == starred, PRIME == 2 == primed
  mask_matrix.resize(matrix.rows(), matrix.columns());

  row_mask = new bool[matrix.rows()];
  col_mask = new bool[matrix.columns()];
  for ( int i = 0 ; i < matrix.rows() ; i++ ) {
    row_mask[i] = false;
  }

  for ( int i = 0 ; i < matrix.columns() ; i++ ) {
    col_mask[i] = false;
  }

  while ( notdone ) {
    switch ( step ) {
      case 0:
        notdone = false;
        break;
      case 1:
        step = step1();
        break;
      case 2:
        step = step2();
        break;
      case 3:
        step = step3();
        break;
      case 4:
        step = step4();
        break;
      case 5:
        step = step5();
        break;
    }
  }

  // Store results
  for ( int row = 0 ; row < matrix.rows() ; row++ )
    for ( int col = 0 ; col < matrix.columns() ; col++ )
      if ( mask_matrix(row,col) == STAR )
        matrix(row,col) = 0;
      else
        matrix(row,col) = -1;

#ifdef DEBUG
  std::cout << "Munkres output matrix:" << std::endl;
  for ( int row = 0 ; row < matrix.rows() ; row++ ) {
    for ( int col = 0 ; col < matrix.columns() ; col++ ) {
      std::cout.width(1);
      std::cout << matrix(row,col) << ",";
    }
    std::cout << std::endl;
  }
  std::cout << std::endl;
#endif

  m = matrix;

  delete [] row_mask;
  delete [] col_mask;
}
Exemplo n.º 11
0
int 
Munkres::step4(void) {
  int rows = matrix.rows();
  int cols = matrix.columns();

  std::list<std::pair<int,int> > seq;
  // use saverow, savecol from step 3.
  std::pair<int,int> z0(saverow, savecol);
  std::pair<int,int> z1(-1,-1);
  std::pair<int,int> z2n(-1,-1);
  seq.insert(seq.end(), z0);
  int row, col = savecol;
  /*
  Increment Set of Starred Zeros

   1. Construct the ``alternating sequence'' of primed and starred zeros:

         Z0 : Unpaired Z' from Step 4.2 
         Z1 : The Z* in the column of Z0
         Z[2N] : The Z' in the row of Z[2N-1], if such a zero exists 
         Z[2N+1] : The Z* in the column of Z[2N]

      The sequence eventually terminates with an unpaired Z' = Z[2N] for some N.
  */
  bool madepair;
  do {
    madepair = false;
    for ( row = 0 ; row < rows ; row++ )
      if ( mask_matrix(row,col) == STAR ) {
        z1.first = row;
        z1.second = col;
        if ( pair_in_list(z1, seq) )
          continue;
        
        madepair = true;
        seq.insert(seq.end(), z1);
        break;
      }

    if ( !madepair )
      break;

    madepair = false;

    for ( col = 0 ; col < cols ; col++ )
      if ( mask_matrix(row,col) == PRIME ) {
        z2n.first = row;
        z2n.second = col;
        if ( pair_in_list(z2n, seq) )
          continue;
        madepair = true;
        seq.insert(seq.end(), z2n);
        break;
      }
  } while ( madepair );

  for ( std::list<std::pair<int,int> >::iterator i = seq.begin() ;
      i != seq.end() ;
      i++ ) {
    // 2. Unstar each starred zero of the sequence.
    if ( mask_matrix(i->first,i->second) == STAR )
      mask_matrix(i->first,i->second) = NORMAL;

    // 3. Star each primed zero of the sequence,
    // thus increasing the number of starred zeros by one.
    if ( mask_matrix(i->first,i->second) == PRIME )
      mask_matrix(i->first,i->second) = STAR;
  }

  // 4. Erase all primes, uncover all columns and rows, 
  for ( int row = 0 ; row < mask_matrix.rows() ; row++ )
    for ( int col = 0 ; col < mask_matrix.columns() ; col++ )
      if ( mask_matrix(row,col) == PRIME )
        mask_matrix(row,col) = NORMAL;
  
  for ( int i = 0 ; i < rows ; i++ ) {
    row_mask[i] = false;
  }

  for ( int i = 0 ; i < cols ; i++ ) {
    col_mask[i] = false;
  }

  // and return to Step 2. 
  return 2;
}
Exemplo n.º 12
0
/*
 *
 * Linear assignment problem solution
 * [modifies matrix in-place.]
 * matrix(row,col): row major format assumed.
 *
 * Assignments are remaining 0 values
 * (extra 0 values are replaced with -1)
 *
 */
void
Munkres::solve(cv::Mat_<int> &m) {
    const unsigned int rows = m.rows,
    columns = m.cols,
    size = std::max<unsigned int>(rows, columns);
    
    if(isDiag) {
        std::cout << "Munkres input matrix:" << std::endl;
        for ( unsigned int row = 0 ; row < rows ; row++ ) {
            for ( unsigned int col = 0 ; col < columns ; col++ ) {
                std::cout.width(4);
                std::cout << m(row, col) << ",";
            }
            std::cout << std::endl;
        }
        std::cout << std::endl;
    }
    
    bool notdone = true;
    int step = 1;
    
    // Copy input matrix
    this->matrix = m;
    
    if ( rows != columns ) {
        // If the input matrix isn't square, make it square
        // and fill the empty values with the largest value present
        // in the matrix.
        extendMat(matrix, size, size, maxValue(matrix));
    }
    
    
    // STAR == 1 == starred, PRIME == 2 == primed
    //    mask_matrix.resize(size, size);
    extendMat(mask_matrix, size, size);
    
    row_mask = new bool[size];
    col_mask = new bool[size];
    for ( unsigned int i = 0 ; i < size ; i++ ) {
        row_mask[i] = false;
    }
    
    for ( unsigned int i = 0 ; i < size ; i++ ) {
        col_mask[i] = false;
    }
    
    // Prepare the matrix values...
    
    // If there were any infinities, replace them with a value greater
    // than the maximum value in the matrix.
    replace_infinites(matrix);
    
    minimize_along_direction(matrix, false);
    minimize_along_direction(matrix, true);
    
    // Follow the steps
    while ( notdone ) {
        switch ( step ) {
            case 0:
                notdone = false;
                // end the step flow
                break;
            case 1:
                step = step1();
                // step is always 2
                break;
            case 2:
                step = step2();
                // step is always either 0 or 3
                break;
            case 3:
                step = step3();
                // step in [3, 4, 5]
                break;
            case 4:
                step = step4();
                // step is always 2
                break;
            case 5:
                step = step5();
                // step is always 3
                break;
        }
    }
    
    // Store results
    for ( unsigned int row = 0 ; row < size ; row++ ) {
        for ( unsigned int col = 0 ; col < size ; col++ ) {
            if ( mask_matrix(row, col) == STAR ) {
                matrix(row, col) = 0;
            } else {
                matrix(row, col) = -1;
            }
        }
    }
    
    if(isDiag) {
        std::cout << "Munkres output matrix:" << std::endl;
        for ( unsigned int row = 0 ; row < rows ; row++ ) {
            for ( unsigned int col = 0 ; col < columns ; col++ ) {
                std::cout.width(2);
                std::cout << matrix(row, col) << ",";
            }
            std::cout << std::endl;
        }
        std::cout << std::endl;
    }
    
    
    // Remove the excess rows or columns that we added to fit the
    // input to a square matrix.
    //    matrix.resize(rows, columns);
    extendMat(matrix, rows, columns);
    
    m = matrix;
    
    delete [] row_mask;
    delete [] col_mask;
}
Exemplo n.º 13
0
/*!
	Linear assignment problem solution
	[modifies matrix in-place.]
	matrix(row,col): row major format assumed.

	Assignments are remaining 0 values on 'matrix'
	(extra 0 values are replaced with -1)

	The correspondence results are stored in the variables
	row2colMap and col2rowMap s.t.

		row2colMap(r) = c means that col c is assigned to row r
		col2rowMap(c) = r means that row r is assigned to column c

	@param initMaps if true the row/col maps are init to invalid values,
	                which help check the mapping by calling CheckMapping()
*/
double Munkres::Solve(const DoubleMatrix& m, UIntVector* row2colMap, 
					UIntVector* col2rowMap) 
{
#ifdef MUNKRES_DEBUG
	std::cout << "Munkres input matrix:" << std::endl;

	for ( int row = 0 ; row < m.rows() ; row++ ) 
	{
		for ( int col = 0 ; col < m.columns() ; col++ ) {
			std::cout.width(8);
			std::cout << m(row,col) << ",";
		}
		std::cout << std::endl;
	}
	std::cout << std::endl;
#endif

	bool notdone = true;
	int step = 1;

	// Copy m, because it need to be modified
	matrix = m;

	// Z_STAR == 1 == starred, Z_PRIME == 2 == primed
	mask_matrix.set_size(matrix.rows(), matrix.columns());
	mask_matrix.fill(0);

	row_mask = new bool[matrix.rows()];
	col_mask = new bool[matrix.columns()];

	for ( unsigned i = 0 ; i < matrix.rows() ; i++ ) {
		row_mask[i] = false;
	}

	for ( unsigned i = 0 ; i < matrix.columns() ; i++ ) {
		col_mask[i] = false;
	}

	while ( notdone ) {
		switch ( step ) {
			case 0:
				notdone = false;
				break;
			case 1:
				step = step1();
				break;
			case 2:
				step = step2();
				break;
			case 3:
				step = step3();
				break;
			case 4:
				step = step4();
				break;
			case 5:
				step = step5();
				break;
		}
	}

	delete[] row_mask;
	delete[] col_mask;

	// Store results
	/*
	for ( unsigned row = 0 ; row < matrix.rows() ; row++ )
		for ( unsigned col = 0 ; col < matrix.columns() ; col++ )
			if ( mask_matrix(row,col) == Z_STAR )
				matrix(row,col) = 0;
			else
				matrix(row,col) = -1;
				
	#ifdef MUNKRES_DEBUG
		std::cout << "Munkres output matrix:" << std::endl;
		for ( int row = 0 ; row < matrix.rows() ; row++ ) {
			for ( int col = 0 ; col < matrix.columns() ; col++ ) {
				std::cout.width(1);
				std::cout << matrix(row,col) << ",";
			}
			std::cout << std::endl;
		}
		std::cout << std::endl;
	#endif		
	*/

	// Store results in the row and col maps s.t.
	// row2colMap(r) = c means that col c is assigned to row r
	// col2rowMap(c) = r means that row r is assigned to column c

	// Init vector to "known" invalid values
	if (row2colMap)
	{
		row2colMap->set_size(matrix.rows());
		row2colMap->fill(UINT_MAX);
	}

	// Init vector to "known" invalid values
	if (col2rowMap)
	{
		col2rowMap->set_size(matrix.cols());
		col2rowMap->fill(UINT_MAX);
	}

	double matchCost = 0;

	for (unsigned row = 0 ; row < matrix.rows() ; ++row)
	{
		for (unsigned col = 0 ; col < matrix.columns() ; ++col)
		{
			if (mask_matrix(row,col) == Z_STAR)
			{
				if (row2colMap)
					(*row2colMap)[row] = col;

				if (col2rowMap)
					(*col2rowMap)[col] = row;

				matchCost += m[row][col]; // use given 'm' not 'matrix'!
			}
		}
	}

	return matchCost;
}
Exemplo n.º 14
0
/*!
	Increment Set of Starred Zeros

   1. Construct the ``alternating sequence'' of primed and starred zeros:

         Z0 : Unpaired Z' from Step 4.2 
         Z1 : The Z* in the column of Z0
         Z[2N] : The Z' in the row of Z[2N-1], if such a zero exists 
         Z[2N+1] : The Z* in the column of Z[2N]

      The sequence eventually terminates with an unpaired Z' = Z[2N] for some N.
*/
int Munkres::step4(void) 
{
	std::list<std::pair<int,int> > seq;
	// use saverow, savecol from step 3.
	std::pair<int,int> z0(saverow, savecol);
	std::pair<int,int> z1(-1,-1);
	std::pair<int,int> z2n(-1,-1);
	seq.insert(seq.end(), z0);
	unsigned row, col = savecol;

	bool madepair;
	do {
		madepair = false;
		for ( row = 0 ; row < matrix.rows() ; row++ )
			if ( mask_matrix(row,col) == Z_STAR ) {
				z1.first = row;
				z1.second = col;
				if ( pair_in_list(z1, seq) )
					continue;
				
				madepair = true;
				seq.insert(seq.end(), z1);
				break;
			}

		if ( !madepair )
			break;

		madepair = false;

		for ( col = 0 ; col < matrix.columns() ; col++ )
			if ( mask_matrix(row,col) == Z_PRIME ) {
				z2n.first = row;
				z2n.second = col;
				if ( pair_in_list(z2n, seq) )
					continue;
				madepair = true;
				seq.insert(seq.end(), z2n);
				break;
			}
	} while ( madepair );

	for ( std::list<std::pair<int,int> >::iterator i = seq.begin() ;
		  i != seq.end() ;
		  i++ ) {
		// 2. Unstar each starred zero of the sequence.
		if ( mask_matrix(i->first,i->second) == Z_STAR )
			mask_matrix(i->first,i->second) = Z_NORMAL;

		// 3. Star each primed zero of the sequence,
		// thus increasing the number of starred zeros by one.
		if ( mask_matrix(i->first,i->second) == Z_PRIME )
			mask_matrix(i->first,i->second) = Z_STAR;
	}

	// 4. Erase all primes, uncover all columns and rows, 
	for ( unsigned row = 0 ; row < mask_matrix.rows() ; row++ )
		for ( unsigned col = 0 ; col < mask_matrix.columns() ; col++ )
			if ( mask_matrix(row,col) == Z_PRIME )
				mask_matrix(row,col) = Z_NORMAL;
	
	for ( unsigned i = 0 ; i < matrix.rows() ; i++ ) {
		row_mask[i] = false;
	}

	for ( unsigned i = 0 ; i < matrix.columns() ; i++ ) {
		col_mask[i] = false;
	}

	// and return to Step 2. 
	return 2;
}
Exemplo n.º 15
0
/*
 *
 * Linear assignment problem solution
 * [modifies matrix in-place.]
 * matrix(row,col): row major format assumed.
 *
 * Assignments are remaining 0 values
 * (extra 0 values are replaced with -1)
 *
 */
void 
Munkres::solve(Matrix<double> &m) {
  const size_t rows = m.rows(),
            columns = m.columns(),
               size = std::max(rows, columns);

#ifdef DEBUG
  std::cout << "Munkres input matrix:" << std::endl;
  for ( size_t row = 0 ; row < rows ; row++ ) {
    for ( size_t col = 0 ; col < columns ; col++ ) {
      std::cout.width(8);
      std::cout << m(row, col) << ",";
    }
    std::cout << std::endl;
  }
  std::cout << std::endl;
#endif

  // Copy input matrix
  this->matrix = m;

  if ( rows != columns ) {
    // If the input matrix isn't square, make it square
    // and fill the empty values with the largest value present
    // in the matrix.
    matrix.resize(size, size, matrix.max());
  }


  // STAR == 1 == starred, PRIME == 2 == primed
  mask_matrix.resize(size, size);

  row_mask = new bool[size];
  col_mask = new bool[size];
  for ( size_t i = 0 ; i < size ; i++ ) {
    row_mask[i] = false;
  }

  for ( size_t i = 0 ; i < size ; i++ ) {
    col_mask[i] = false;
  }

  // Prepare the matrix values...

  // If there were any infinities, replace them with a value greater
  // than the maximum value in the matrix.
  replace_infinites(matrix);

  minimize_along_direction(matrix, false);
  minimize_along_direction(matrix, true);

  // Follow the steps
  int step = 1;
  while ( step ) {
    switch ( step ) {
      case 1:
        step = step1();
        // step is always 2
        break;
      case 2:
        step = step2();
        // step is always either 0 or 3
        break;
      case 3:
        step = step3();
        // step in [3, 4, 5]
        break;
      case 4:
        step = step4();
        // step is always 2
        break;
      case 5:
        step = step5();
        // step is always 3
        break;
    }
  }

  // Store results
  for ( size_t row = 0 ; row < size ; row++ ) {
    for ( size_t col = 0 ; col < size ; col++ ) {
      if ( mask_matrix(row, col) == STAR ) {
        matrix(row, col) = 0;
      } else {
        matrix(row, col) = -1;
      }
    }
  }

#ifdef DEBUG
  std::cout << "Munkres output matrix:" << std::endl;
  for ( size_t row = 0 ; row < rows ; row++ ) {
    for ( size_t col = 0 ; col < columns ; col++ ) {
      std::cout.width(1);
      std::cout << matrix(row, col) << ",";
    }
    std::cout << std::endl;
  }
  std::cout << std::endl;
#endif


  // Remove the excess rows or columns that we added to fit the
  // input to a square matrix.
  matrix.resize(rows, columns);

  m = matrix;

  delete [] row_mask;
  delete [] col_mask;
}