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rmq_support_sparse_table.hpp
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/* sdsl - succinct data structures library
Copyright (C) 2009 Simon Gog
This program 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 of the License, or
(at your option) any later version.
This program 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.
You should have received a copy of the GNU General Public License
along with this program. If not, see http://www.gnu.org/licenses/ .
*/
/*! \file rmq_support_sparse_table.hpp
\brief rmq_support_sparse_table.hpp contains the class rmq_support_sparse_table.
\author Simon Gog
*/
#ifndef INCLUDED_SDSL_RMQ_SUPPORT_SPARSE_TABLE
#define INCLUDED_SDSL_RMQ_SUPPORT_SPARSE_TABLE
#include "rmq_support.hpp"
#include "int_vector.hpp"
#include <ostream>
//! Namespace for the succinct data structure library.
namespace sdsl
{
template<class t_rac = int_vector<>, bool t_min=true>
class rmq_support_sparse_table;
// see http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2002/n1406.pdf for a proposal for a better solution
template<class t_rac = int_vector<> >
struct range_maximum_support_sparse_table {
typedef rmq_support_sparse_table<t_rac, false> type;
};
//! A class to support range minimum or range maximum queries on a random access container.
/*!
* \tparam t_rac Type of random access container for which the structure should be build.
* \tparam t_min Specifies whether the data structure should answer range min/max queries (mimumum=true)
*
* \par Reference
* Michael A. Bender, Martin Farach-Colton:
* The LCA Problem Revisited.
* LATIN 2000: 88-94
*
* \par Time complexity
* \f$ \Order{1} \f$ for the range minimum/maximum queries.
* \par Space complexity:
* \f$ \Order{n\log^2 n} \f$ bits for the data structure ( \f$ n=size() \f$ ). We used bit compression to get a good result in practice.
*/
template<class t_rac, bool t_min>
class rmq_support_sparse_table
{
const t_rac* m_v; // pointer to the supported random access container
bit_vector::size_type m_k; // size of m_table
int_vector<>* m_table;
typedef min_max_trait<t_rac, t_min> mm_trait;
void copy(const rmq_support_sparse_table& rm) {
m_v = rm.m_v;
m_k = rm.m_k;
if (m_table != NULL) {
delete [] m_table;
m_table = NULL;
}
if (m_k > 0) {
m_table = new int_vector<>[m_k];
for (size_type i=0; i<m_k; ++i)
m_table[i] = rm.m_table[i];
}
}
public:
typedef typename t_rac::size_type size_type;
typedef typename t_rac::size_type value_type;
rmq_support_sparse_table(const t_rac* v=NULL):m_v(v), m_k(0), m_table(NULL) {
if (m_v == NULL)
return;
const size_type n = m_v->size();
if (n < 2) // for n<2 the queries could be answerd without any table
return;
size_type k=0;
while (2*(1ULL<<k) < n) ++k; // calculate maximal
if (!(m_table == NULL))
delete [] m_table;
m_table = new int_vector<>[k];
m_k = k;
for (size_type i=0; i<k; ++i) {
m_table[i] = int_vector<>(n-(1<<(i+1))+1, 0, i+1);
}
for (size_type i=0; i<n-1; ++i) {
if (!mm_trait::compare((*m_v)[i], (*m_v)[i+1]))
m_table[0][i] = 1;
}
for (size_type i=1; i<k; ++i) {
for (size_type j=0; j<m_table[i].size(); ++j) {
m_table[i][j] = mm_trait::compare((*m_v)[j+m_table[i-1][j]], (*m_v)[j+(1<<i)+m_table[i-1][j+(1<<i)]]) ? m_table[i-1][j] : (1<<i)+m_table[i-1][j+(1<<i)];
}
}
}
//! Copy constructor
rmq_support_sparse_table(const rmq_support_sparse_table& rm) {
if (this != &rm) { // if v is not the same object
copy(rm);
}
}
~rmq_support_sparse_table() {
if (m_table != NULL)
delete [] m_table;
}
rmq_support_sparse_table& operator=(const rmq_support_sparse_table& rm) {
if (this != &rm) {
copy(rm);
}
return *this;
}
void swap(rmq_support_sparse_table& rm) {
std::swap(m_k, rm.m_k);
std::swap(m_table, rm.m_table);
}
void set_vector(const t_rac* v) {
m_v = v;
}
//! Range minimum/maximum query for the supported random access container v.
/*!
* \param l Leftmost position of the interval \f$[\ell..r]\f$.
* \param r Rightmost position of the interval \f$[\ell..r]\f$.
* \return The minimal index i with \f$\ell \leq i \leq r\f$ for which \f$ v[i] \f$ is minimal/maximal.
* \pre
* - r < size()
* - \f$ \ell \leq r \f$
* \par Time complexity
* \f$ \Order{1} \f$
*/
size_type operator()(const size_type l, const size_type r)const {
assert(l <= r); assert(r < size());
if (l==r)
return l;
if (l+1 == r)
return mm_trait::compare((*m_v)[l],(*m_v)[r]) ? l : r;
size_type k = bits::hi(r-l);
const size_type rr = r-(1<<k)+1;
return mm_trait::compare((*m_v)[l+m_table[k-1][l]], (*m_v)[rr+m_table[k-1][rr]]) ? l+m_table[k-1][l] : rr+m_table[k-1][rr];
}
size_type size()const {
if (m_v == NULL)
return 0;
else
return m_v->size();
}
size_type serialize(std::ostream& out, structure_tree_node* v=NULL, std::string name="")const {
size_type written_bytes = 0;
structure_tree_node* child = structure_tree::add_child(v, name, util::class_name(*this));
written_bytes += write_member(m_k, out);
if (m_k > 0) {
assert(m_table != NULL);
for (size_type i=0; i < m_k; ++i)
written_bytes += m_table[i].serialize(out);
}
structure_tree::add_size(child, written_bytes);
return written_bytes;
}
void load(std::istream& in, const t_rac* v) {
set_vector(v);
read_member(m_k, in);
if (m_k >0) {
if (m_table != NULL)
delete [] m_table;
m_table = new int_vector<>[m_k];
for (size_type i=0; i < m_k; ++i)
m_table[i].load(in);
}
}
};
}// end namespace sds;
#endif