FenwickFixedF.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 FenwickFixedF : 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;
    size_t Size;
 
  public:
    FenwickFixedF() : Size(0) {}
 
    FenwickFixedF(uint64_t sequence[], size_t size) : Tree(pos(size) + 1), Size(size) {
        for (size_t j = 1; j <= Size; j++) Tree[pos(j)] = sequence[j - 1];
 
        for (size_t m = 2; m <= Size; m <<= 1) {
            for (size_t idx = m; idx <= Size; idx += m) Tree[pos(idx)] += Tree[pos(idx - m / 2)];
        }
    }
 
    virtual uint64_t prefix(size_t idx) {
        uint64_t sum = 0;
 
        while (idx != 0) {
            sum += Tree[pos(idx)];
            idx = clear_rho(idx);
        }
 
        return sum;
    }
 
    virtual void add(size_t idx, int64_t inc) {
        while (idx <= Size) {
            Tree[pos(idx)] += inc;
            idx += mask_rho(idx);
        }
    }
 
    using SearchablePrefixSums::find;
    virtual size_t find(uint64_t *val) {
        size_t node = 0;
 
        for (size_t m = mask_lambda(Size); m != 0; m >>= 1) {
            if (node + m > Size) continue;
 
            uint64_t value = Tree[pos(node + m)];
 
            if (*val >= value) {
                node += m;
                *val -= value;
            }
        }
 
        return node;
    }
 
    using SearchablePrefixSums::compFind;
    virtual size_t compFind(uint64_t *val) {
        size_t node = 0;
 
        for (size_t m = mask_lambda(Size); m != 0; m >>= 1) {
            if (node + m > Size) continue;
 
            uint64_t value = (BOUND << rho(node + m)) - Tree[pos(node + m)];
 
            if (*val >= value) {
                node += m;
                *val -= value;
            }
        }
 
        return node;
    }
 
    virtual void push(uint64_t val) {
        size_t p = pos(++Size);
        Tree.resize(p + 1);
        Tree[p] = val;
 
        if ((Size & 1) == 0) {
            for (size_t idx = Size - 1; rho(idx) < rho(Size); idx = clear_rho(idx)) Tree[p] += Tree[pos(idx)];
        }
    }
 
    virtual void pop() {
        Size--;
        Tree.popBack();
    }
 
    virtual void grow(size_t space) { Tree.grow(space); }
 
    virtual void reserve(size_t space) { Tree.reserve(space); }
 
    using Expandable::trimToFit;
    virtual void trim(size_t space) { Tree.trim(space); };
 
    virtual void resize(size_t space) { Tree.resize(space); }
 
    virtual void size(size_t space) { Tree.size(space); }
 
    virtual size_t size() const { return Size; }
 
    virtual size_t bitCount() const { return Tree.bitCount() - sizeof(Tree) * 8 + sizeof(*this) * 8; }
 
  private:
    static inline size_t holes(size_t idx) { return idx >> 14; }
 
    static inline size_t pos(size_t idx) { return idx + holes(idx); }
 
    friend std::ostream &operator<<(std::ostream &os, const FenwickFixedF<BOUND, AT> &ft) {
        os.write((char *)&ft.Size, sizeof(uint64_t));
        return os << ft.Tree;
    }
 
    friend std::istream &operator>>(std::istream &is, FenwickFixedF<BOUND, AT> &ft) {
        is.read((char *)&ft.Size, sizeof(uint64_t));
        return is >> ft.Tree;
    }
};
 
} // namespace sux::util