static void discharge(MatrixT const &C,
MatrixT &F,
MatrixT &excess,
MatrixT &height,
MatrixT &seen,
graphblas::IndexType u)
{
graphblas::IndexType num_nodes, cols;
C.get_shape(num_nodes, cols);
while (excess.get_value_at(0, u) > 0)
{
if (seen.get_value_at(0, u) < num_nodes)
{
graphblas::IndexType v = seen.get_value_at(0, u);
if (((C.get_value_at(u, v) - F.get_value_at(u, v)) > 0) &&
(height.get_value_at(0, u) > height.get_value_at(0, v)))
{
push(C, F, excess, u, v);
}
else
{
seen.set_value_at(0, u, seen.get_value_at(0, u) + 1);
}
}
else
{
relabel(C, F, height, u);
seen.set_value_at(0, u, 0);
}
}
}
void pretty_print_matrix(std::ostream &ostr, MatrixT const &mat)
{
IndexType rows, cols;
mat.get_shape(rows, cols);
typename MatrixT::ScalarType zero(mat.get_zero());
for (IndexType row = 0; row < rows; ++row)
{
ostr << ((row == 0) ? "[[" : " [");
if (cols > 0)
{
auto val = mat.get_value_at(row, 0);
if (val == zero)
ostr << " ";
else
ostr << val;
}
for (IndexType col = 1; col < cols; ++col)
{
auto val = mat.get_value_at(row, col);
if (val == zero)
ostr << ", ";
else
ostr << ", " << val;
}
ostr << ((row == rows - 1) ? "]]\n" : "]\n");
}
}
void row_index_of(MatrixT &mat)
{
graphblas::IndexType rows, cols;
mat.get_shape(rows, cols);
for (IndexType i = 0; i < rows; ++i)
{
for (IndexType j = 0; j < cols; ++j)
{
auto mat_ij = mat.get_value_at(i, j);
if (mat_ij != mat.get_zero())
{
mat.set_value_at(i, j, i);
}
}
}
}
typename MatrixT::ScalarType sum(MatrixT const &m)
{
using T = typename MatrixT::ScalarType;
graphblas::IndexType rows, cols;
m.get_shape(rows, cols);
T sum = static_cast<T>(0);
for (graphblas::IndexType i = 0; i < rows; ++i)
{
for (graphblas::IndexType j = 0; j < cols; ++j)
{
sum += m[i][j];
}
}
return sum;
}
static void relabel(MatrixT const &C,
MatrixT const &F,
MatrixT &height,
graphblas::IndexType u)
{
using T = typename MatrixT::ScalarType;
graphblas::IndexType num_nodes, cols;
C.get_shape(num_nodes, cols);
T min_height = std::numeric_limits<T>::max();
for (graphblas::IndexType v = 0; v < num_nodes; ++v)
{
if ((C.get_value_at(u, v) - F.get_value_at(u, v)) > 0)
{
T a = height.get_value_at(0, v);
min_height = std::min(min_height, a);
height.set_value_at(0, u, min_height + 1);
}
}
}
typename MatrixT::ScalarType maxflow(MatrixT const &capacity,
graphblas::IndexType source,
graphblas::IndexType sink)
{
using T = typename MatrixT::ScalarType;
graphblas::IndexType rows, cols;
capacity.get_shape(rows,cols);
graphblas::IndexType num_nodes = rows;
MatrixT flow(rows,cols);
MatrixT height(1, num_nodes);
MatrixT excess(1, num_nodes);
MatrixT seen(1, num_nodes);
std::vector<graphblas::IndexType> list;
for (graphblas::IndexType i = 0; i < num_nodes; ++i)
{
if ((i != source) && (i != sink))
{
list.push_back(i);
}
}
height.set_value_at(0, source, num_nodes);
excess.set_value_at(0, source,
std::numeric_limits<T>::max());
for (graphblas::IndexType i = 0; i < num_nodes; ++i)
{
push(capacity, flow, excess, source, i);
}
graphblas::IndexType p = 0;
while (p < (num_nodes - 2))
{
graphblas::IndexType u = list[p];
T old_height = height.get_value_at(0, u);
discharge(capacity, flow, excess, height, seen, u);
if (height.get_value_at(0, u) > old_height)
{
graphblas::IndexType t = list[p];
list.erase(list.begin() + p);
list.insert(list.begin() + 0, t);
p = 0;
}
else
{
p += 1;
}
}
T maxflow = static_cast<T>(0);
for (graphblas::IndexType i = 0; i < num_nodes; ++i)
{
maxflow += flow.get_value_at(source, i);
}
return maxflow;
}
