FenwickFixedL.hpp

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/*
 * Sux: Succinct data structures
 *
 * Copyright (C) 2019-2020 Stefano Marchini
 *
 *  This library is free software; you can redistribute it and/or modify it
 *  under the terms of the GNU Lesser General Public License as published by the Free
 *  Software Foundation; either version 3 of the License, or (at your option)
 *  any later version.
 *
 * This library is free software; you can redistribute it and/or modify it under
 * the terms of the GNU General Public License as published by the Free Software
 * Foundation; either version 3, or (at your option) any later version.
 *
 * This 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 General Public License for more details.
 *
 * Under Section 7 of GPL version 3, you are granted additional permissions
 * described in the GCC Runtime Library Exception, version 3.1, as published by
 * the Free Software Foundation.
 *
 * You should have received a copy of the GNU General Public License and a copy of
 * the GCC Runtime Library Exception along with this program; see the files
 * COPYING3 and COPYING.RUNTIME respectively.  If not, see
 * <http://www.gnu.org/licenses/>.
 */
 
#pragma once
 
#include "SearchablePrefixSums.hpp"
#include "Vector.hpp"
 
namespace sux::util {
 
template <size_t BOUND, AllocType AT = MALLOC> class FenwickFixedL : public SearchablePrefixSums, public Expandable {
  public:
    static constexpr size_t BOUNDSIZE = ceil_log2_plus1(BOUND);
    static_assert(BOUNDSIZE >= 1 && BOUNDSIZE <= 64, "Leaves can't be stored in a 64-bit word");
 
  protected:
    Vector<uint64_t, AT> Tree[64];
    size_t Levels, Size;
 
  public:
    FenwickFixedL() : Levels(0), Size(0) {}
 
    FenwickFixedL(uint64_t sequence[], size_t size) : Levels(size != 0 ? lambda(size) + 1 : 1), Size(size) {
        this->size(size ? size : 1);
 
        for (size_t l = 0; l < Levels; l++) {
            for (size_t node = 1ULL << l; node <= size; node += 1ULL << (l + 1)) {
                size_t sequence_idx = node - 1;
                uint64_t value = sequence[sequence_idx];
                for (size_t j = 0; j < l; j++) {
                    sequence_idx >>= 1;
                    value += Tree[j][sequence_idx];
                }
 
                Tree[l][node >> (l + 1)] = value;
            }
        }
    }
 
    virtual uint64_t prefix(size_t idx) {
        uint64_t sum = 0;
 
        while (idx != 0) {
            const int height = rho(idx);
            size_t level_idx = idx >> (1 + height);
            sum += Tree[height][level_idx];
 
            idx = clear_rho(idx);
        }
 
        return sum;
    }
 
    virtual void add(size_t idx, int64_t inc) {
        while (idx <= Size) {
            const int height = rho(idx);
            size_t level_idx = idx >> (1 + height);
            Tree[height][level_idx] += inc;
 
            idx += mask_rho(idx);
        }
    }
 
    using SearchablePrefixSums::find;
    virtual size_t find(uint64_t *val) {
        size_t node = 0, idx = 0;
 
        for (size_t height = Levels - 1; height != SIZE_MAX; height--) {
            size_t pos = idx;
 
            idx <<= 1;
 
            if (pos >= Tree[height].size()) continue;
 
            uint64_t value = Tree[height][pos];
            if (*val >= value) {
                idx++;
                *val -= value;
                node += 1ULL << height;
            }
        }
 
        return min(node, Size);
    }
 
    using SearchablePrefixSums::compFind;
    virtual size_t compFind(uint64_t *val) {
        size_t node = 0, idx = 0;
 
        for (size_t height = Levels - 1; height != SIZE_MAX; height--) {
            size_t pos = idx;
 
            idx <<= 1;
 
            if (pos >= Tree[height].size()) continue;
 
            uint64_t value = (BOUND << height) - Tree[height][pos];
            if (*val >= value) {
                idx++;
                *val -= value;
                node += 1ULL << height;
            }
        }
 
        return min(node, Size);
    }
 
    virtual void push(uint64_t val) {
        Levels = lambda(++Size) + 1;
 
        int height = rho(Size);
        size_t level_idx = Size >> (1 + height);
        Tree[height].resize(level_idx + 1);
 
        Tree[height][level_idx] = val;
 
        size_t idx = level_idx << 1;
        for (size_t h = height - 1; h != SIZE_MAX; h--) {
            Tree[height][level_idx] += Tree[h][idx];
            idx = (idx << 1) + 1;
        }
    }
 
    virtual void pop() {
        int height = rho(Size--);
        Tree[height].popBack();
    }
 
    virtual void grow(size_t space) {
        size_t levels = lambda(space) + 1;
        for (size_t i = 0; i < levels; i++) Tree[i].grow((space + (1ULL << i)) / (1ULL << (i + 1)));
    }
 
    virtual void reserve(size_t space) {
        size_t levels = lambda(space) + 1;
        for (size_t i = 0; i < levels; i++) Tree[i].reserve((space + (1ULL << i)) / (1ULL << (i + 1)));
    }
 
    using Expandable::trimToFit;
    virtual void trim(size_t space) {
        size_t levels = lambda(space) + 1;
        for (size_t i = 0; i < levels; i++) Tree[i].trim((space + (1ULL << i)) / (1ULL << (i + 1)));
    }
 
    virtual void resize(size_t space) {
        size_t levels = lambda(space) + 1;
        for (size_t i = 0; i < levels; i++) Tree[i].resize((space + (1ULL << i)) / (1ULL << (i + 1)));
    }
 
    virtual void size(size_t space) {
        size_t levels = lambda(space) + 1;
        for (size_t i = 0; i < levels; i++) Tree[i].size((space + (1ULL << i)) / (1ULL << (i + 1)));
    }
 
    virtual size_t size() const { return Size; }
 
    virtual size_t bitCount() const {
        size_t ret = sizeof(*this) * 8;
        for (size_t i = 0; i < 64; i++) ret += Tree[i].bitCount() - sizeof(Tree[i]) * 8;
        return ret;
    }
 
  private:
    friend std::ostream &operator<<(std::ostream &os, const FenwickFixedL<BOUND, AT> &ft) {
        os.write((char *)&ft.Size, sizeof(uint64_t));
        os.write((char *)&ft.Levels, sizeof(uint64_t));
        for (size_t i = 0; i < 64; i++) os << ft.Tree[i];
        return os;
    }
 
    friend std::istream &operator>>(std::istream &is, FenwickFixedL<BOUND, AT> &ft) {
        is.read((char *)&ft.Size, sizeof(uint64_t));
        is.read((char *)&ft.Levels, sizeof(uint64_t));
        for (size_t i = 0; i < ft.Levels; i++) is >> ft.Tree[i];
        return is;
    }
};
 
} // namespace sux::util