make_arrangement.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
 
// lal includes
#include <lal/linear_arrangement.hpp>
#include <lal/graphs/rooted_tree.hpp>
 
namespace lal {
namespace detail {
 
// -- for rooted trees
 
template <class container>
void make_arrangement_permutations(
    const graphs::rooted_tree& T,
    const node r,
    const container& data,
    position& pos,
    linear_arrangement& arr
)
noexcept
{
    // number of children of 'r' with respect to the tree's root
    const uint64_t d_out = T.get_out_degree(r);
 
    // vertex 'r' is a leaf
    if (d_out == 0) {
        arr.assign(r, pos++);
        return;
    }
    const auto& interval = data[r];
    for (std::size_t i = 0; i < interval.size(); ++i) {
        const node vi = interval[i];
        if (vi == r) {
            arr.assign(vi, pos++);
        }
        else {
            make_arrangement_permutations(T, vi, data, pos, arr);
        }
    }
}
 
template <class container>
[[nodiscard]] linear_arrangement make_arrangement_permutations
(const graphs::rooted_tree& T, const container& data)
noexcept
{
    linear_arrangement arr(T.get_num_nodes());
    position pos = 0;
    make_arrangement_permutations(T, T.get_root(), data, pos, arr);
    return arr;
}
 
// -----------------------------------------------------------------------------
// -- for free trees
 
template <class container>
void make_arrangement_permutations(
    const graphs::free_tree& T,
    node parent, node u,
    const container& data,
    position& pos, linear_arrangement& arr
)
noexcept
{
    // number of children of 'u' with respect to the tree's root
    const uint64_t d_out = T.get_degree(u) - (u == parent ? 0 : 1);
 
    // vertex 'u' is a leaf in the rooted version of T
    if (d_out == 0) {
        arr.assign(u, pos++);
        return;
    }
    const auto& interval = data[u];
    for (std::size_t i = 0; i < interval.size(); ++i) {
        const node vi = interval[i];
        if (vi == u) {
            arr.assign(vi, pos++);
        }
        else {
            make_arrangement_permutations(T, u, vi, data, pos, arr);
        }
    }
}
 
template <class container>
[[nodiscard]] linear_arrangement make_arrangement_permutations
(const graphs::free_tree& T, node root, const container& data)
noexcept
{
    linear_arrangement arr(T.get_num_nodes());
    position pos = 0;
    make_arrangement_permutations(T, root, root, data, pos, arr);
    return arr;
}
 
} // -- namespace detail
} // -- namespace lal