coloring_welsh_powell Module Subroutine

    module subroutine coloring_welsh_powell(self, graph)
        implicit none
        class(type_coloring), intent(inout) :: self
        class(type_crs_adjacency_element), intent(in) :: graph

        integer(int32) :: num_elements, i, v
        integer(int32), allocatable :: perm(:)

        num_elements = graph%get_num_elements()

        if (allocated(self%color)) call deallocate_array(self%color)
        call allocate_array(self%color, length=num_elements)
        self%color = 0

        ! ステップ1: 次数降順の処理順序(perm)を取得
        call get_welsh_powell_order(graph, perm)

        ! ステップ2: ソートされた順序で要素を着色
        do i = 1, num_elements
            v = perm(i)
            self%color(v) = find_smallest_available_color(v, graph, self%color)
        end do

        ! ステップ3: 結果を構造体に整理
        call self%populate()

        call deallocate_array(perm)
    end subroutine coloring_welsh_powell