Dopt_utils.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/
 *
 *     Juan Luis Esteban (esteban@cs.upc.edu)
 *         LOGPROG: Logics and Programming Research Group
 *         Office 110, Omega building
 *         Jordi Girona St 1-3, Campus Nord UPC, 08034 Barcelona.   CATALONIA, SPAIN
 *         Webpage: https://www.cs.upc.edu/~esteban/
 *
 *     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 <vector>
 
// lal includes
#include <lal/linear_arrangement.hpp>
#include <lal/graphs/rooted_tree.hpp>
#include <lal/detail/array.hpp>
#include <lal/iterators/E_iterator.hpp>
#include <lal/detail/graphs/size_subtrees.hpp>
#include <lal/detail/sorting/counting_sort.hpp>
#include <lal/detail/properties/tree_centroid.hpp>
 
namespace lal {
namespace detail {
 
namespace Dopt_utils {
 
typedef unsigned char place;
typedef unsigned char side;
 
static constexpr place PLACE_LEFT_OF = 0;
static constexpr place PLACE_RIGHT_OF = 1;
static constexpr place PLACE_NONE_OF = 2;
 
static constexpr side RIGHT_SIDE = 0;
static constexpr side LEFT_SIDE  = 1;
 
// if s = 0 then (s+1)&0x1 = 1
// if s = 1 then (s+1)&0x1 = 0
static inline constexpr side other_side(side s) noexcept { return ((s + 1)&0x1); }
 
static inline constexpr bool is_even(uint64_t i) noexcept { return (i&0x1) == 0; }
 
static constexpr char LEFT_ANCHOR = -1;
static constexpr char RIGHT_ANCHOR = 1;
static constexpr char NO_ANCHOR = 0;
static constexpr char ANCHOR = 1;
 
/* ************************************************************************** */
/* ----------------------- ROOTED ADJACENCY LISTS --------------------------- */
 
/* Functions to calculate the sorted, rooted
 * adjacency list of rooted and free trees.
 */
 
template <sorting::sort_type type>
void make_sorted_adjacency_list_rooted
(const graphs::rooted_tree& t, std::vector<std::vector<node_size>>& L)
noexcept
{
    const uint64_t n = t.get_num_nodes();
    const node r = t.get_root();
 
    // for every edge (u,v), store the tuple
    //    (n_v, (u,v))
    // at L[u]
    array<edge_size> edge_list(n - 1);
 
    {
    const std::size_t k = t.are_size_subtrees_valid() ? 0 : t.get_num_nodes();
    array<uint64_t> size_subtrees(k, 0);
 
    sorting::countingsort::memory<edge_size> memcs(n, n);
    auto it = edge_list.begin();
 
    iterators::E_iterator<graphs::rooted_tree> E_it(t);
    if (t.are_size_subtrees_valid()) {
        // use the sizes that are already calculated
        while (not E_it.end()) {
            const edge e = E_it.get_edge();
            const node v = e.second;
            const uint64_t suv = t.get_num_nodes_subtree(v);
            *it++ = {e, suv};
            ++memcs.count[suv];
 
            E_it.next();
        }
    }
    else {
        // fill in the size of the subtrees
        get_size_subtrees(t, r, size_subtrees.begin());
        while (not E_it.end()) {
            const edge e = E_it.get_edge();
            const node v = e.second;
            const uint64_t suv = size_subtrees[v];
            *it++ = {e, suv};
            ++memcs.count[suv];
 
            E_it.next();
        }
    }
 
    // sort all tuples in L using the size of the subtree
    sorting::counting_sort
        <edge_size, type, true>
        (
            edge_list.begin(), edge_list.end(), n,
            [](const edge_size& T) -> std::size_t { return T.size; },
            memcs
        );
    }
 
    // M[u] : adjacency list of vertex u sorted decreasingly according
    // to the sizes of the subtrees.
    // This is used to find the optimal projective arrangement of the tree.
    for (const auto& T : edge_list) {
        const auto [u, v] = T.e;
        const uint64_t nv = T.size;
        L[u].push_back({v,nv});
#if defined DEBUG
        assert(t.has_edge(u,v));
#endif
    }
 
#if defined DEBUG
    for (node u = 0; u < n; ++u) {
        assert(L[u].size() == t.get_out_degree(u));
    }
#endif
}
 
} // -- namespcae proj_plan_opt_utils
} // -- namespace detail
} // -- namespace lal