size_subtrees.hpp

/*********************************************************************
 *
 * Linear Arrangement Library - A library that implements a collection
 * algorithms for linear arrangments of graphs.
 *
 * Copyright (C) 2019 - 2024
 *
 * This file is part of Linear Arrangement Library. The full code is available
 * at:
 *      https://github.com/LAL-project/linear-arrangement-library.git
 *
 * Linear Arrangement Library is free software: you can redistribute it
 * and/or modify it under the terms of the GNU Affero General Public License
 * as published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * Linear Arrangement Library is distributed in the hope that it will be
 * useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with Linear Arrangement Library.  If not, see <http://www.gnu.org/licenses/>.
 *
 * Contact:
 *
 *     Lluís Alemany Puig (lluis.alemany.puig@upc.edu)
 *         LQMC (Quantitative, Mathematical, and Computational Linguisitcs)
 *         CQL (Complexity and Quantitative Linguistics Lab)
 *         Jordi Girona St 1-3, Campus Nord UPC, 08034 Barcelona.   CATALONIA, SPAIN
 *         Webpage: https://cqllab.upc.edu/people/lalemany/
 *
 *     Ramon Ferrer i Cancho (rferrericancho@cs.upc.edu)
 *         LQMC (Quantitative, Mathematical, and Computational Linguisitcs)
 *         CQL (Complexity and Quantitative Linguistics Lab)
 *         Office 220, Omega building
 *         Jordi Girona St 1-3, Campus Nord UPC, 08034 Barcelona.   CATALONIA, SPAIN
 *         Webpage: https://cqllab.upc.edu/people/rferrericancho/
 *
 ********************************************************************/
 
#pragma once
 
// C++ includes
#if defined DEBUG
#include <cassert>
#endif
#include <tuple>
 
// lal includes
#include <lal/graphs/rooted_tree.hpp>
#include <lal/graphs/free_tree.hpp>
#include <lal/detail/type_traits/is_pointer_iterator.hpp>
#include <lal/detail/pairs_utils.hpp>
 
namespace lal {
namespace detail {
 
template <
    class tree_t,
    std::enable_if_t< std::is_base_of_v<graphs::tree, tree_t>, bool> = true
>
void get_size_subtrees
(
    const tree_t& t,
    const node u,
    const node v,
    uint64_t * const sizes
)
noexcept
{
    sizes[v] = 1;
 
    if constexpr (std::is_base_of_v<graphs::rooted_tree, tree_t>) {
        for (const node w : t.get_out_neighbors(v)) {
            if (w == u) { continue; }
            get_size_subtrees(t, v, w, sizes);
            sizes[v] += sizes[w];
        }
        for (const node w : t.get_in_neighbors(v)) {
            if (w == u) { continue; }
            get_size_subtrees(t, v, w, sizes);
            sizes[v] += sizes[w];
        }
    }
    else {
        for (const node w : t.get_neighbors(v)) {
            if (w == u) { continue; }
            get_size_subtrees(t, v, w, sizes);
            sizes[v] += sizes[w];
        }
    }
}
 
template <
    class tree_t,
    std::enable_if_t< std::is_base_of_v<graphs::tree, tree_t>, bool> = true
>
inline void get_size_subtrees(
    const tree_t& t,
    const node r,
    uint64_t * const sizes
)
noexcept
{
#if defined DEBUG
    assert(sizes != nullptr);
#endif
    get_size_subtrees(t, t.get_num_nodes(), r, sizes);
}
 
template <
    class tree_t,
    typename iterator_t,
    std::enable_if_t<
        std::is_base_of_v<graphs::tree, tree_t>
        and is_pointer_iterator_v<edge_size, iterator_t>,
        bool
    > = true
>
[[nodiscard]]
uint64_t calculate_bidirectional_sizes
(
    const tree_t& t,
    const uint64_t n,
    const node u,
    const node v,
    iterator_t& it
)
noexcept
{
    uint64_t s = 1;
    if constexpr (std::is_base_of_v<graphs::rooted_tree, tree_t>) {
        for (const node w : t.get_out_neighbors(v)) {
            if (w == u) { continue; }
            s += calculate_bidirectional_sizes(t,n, v, w, it);
        }
        for (const node w : t.get_in_neighbors(v)) {
            if (w == u) { continue; }
            s += calculate_bidirectional_sizes(t,n, v, w, it);
        }
    }
    else {
        for (const node w : t.get_neighbors(v)) {
            if (w == u) { continue; }
            s += calculate_bidirectional_sizes(t,n, v, w, it);
        }
    }
 
    *it++ = {edge(u,v), s};
    *it++ = {edge(v,u), n - s};
    return s;
}
 
template <
    class tree_t,
    typename iterator_t,
    std::enable_if_t<
        std::is_base_of_v<graphs::tree, tree_t>
        and is_pointer_iterator_v<edge_size, iterator_t>,
        bool
    > = true
>
inline void calculate_bidirectional_sizes(
    const tree_t& t,
    const uint64_t n,
    const node x,
    iterator_t it
)
noexcept
{
    if constexpr (std::is_base_of_v<graphs::rooted_tree, tree_t>) {
        for (const node y : t.get_out_neighbors(x)) {
            std::ignore = calculate_bidirectional_sizes(t,n, x, y, it);
        }
        for (const node y : t.get_in_neighbors(x)) {
            std::ignore = calculate_bidirectional_sizes(t,n, x, y, it);
        }
    }
    else {
        for (const node y : t.get_neighbors(x)) {
            std::ignore = calculate_bidirectional_sizes(t,n, x, y, it);
        }
    }
}
 
} // -- namespace detail
} // -- namespace lal