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162 lines
4.5 KiB
C++
162 lines
4.5 KiB
C++
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/*
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Copyright (c) Alexander Zaitsev <zamazan4ik@gmail.com>, 2016
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Distributed under the Boost Software License, Version 1.0. (See
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accompanying file LICENSE_1_0.txt or copy at
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http://www.boost.org/LICENSE_1_0.txt)
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See http://www.boost.org/ for latest version.
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*/
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/// \file is_palindrome.hpp
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/// \brief Checks the input sequence on palindrome.
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/// \author Alexander Zaitsev
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#ifndef BOOST_ALGORITHM_IS_PALINDROME_HPP
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#define BOOST_ALGORITHM_IS_PALINDROME_HPP
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#include <iterator>
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#include <functional>
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#include <cstring>
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#include <boost/range/begin.hpp>
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#include <boost/range/end.hpp>
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namespace boost { namespace algorithm {
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/// \fn is_palindrome ( BidirectionalIterator begin, BidirectionalIterator end, Predicate p )
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/// \return true if the entire sequence is palindrome
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///
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/// \param begin The start of the input sequence
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/// \param end One past the end of the input sequence
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/// \param p A predicate used to compare the values.
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///
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/// \note This function will return true for empty sequences and for palindromes.
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/// For other sequences function will return false.
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/// Complexity: O(N).
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template <typename BidirectionalIterator, typename Predicate>
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bool is_palindrome(BidirectionalIterator begin, BidirectionalIterator end, Predicate p )
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{
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if(begin == end)
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{
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return true;
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}
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--end;
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while(begin != end)
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{
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if(!p(*begin, *end))
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{
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return false;
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}
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++begin;
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if(begin == end)
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{
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break;
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}
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--end;
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}
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return true;
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}
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/// \fn is_palindrome ( BidirectionalIterator begin, BidirectionalIterator end )
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/// \return true if the entire sequence is palindrome
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///
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/// \param begin The start of the input sequence
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/// \param end One past the end of the input sequence
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///
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/// \note This function will return true for empty sequences and for palindromes.
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/// For other sequences function will return false.
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/// Complexity: O(N).
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template <typename BidirectionalIterator>
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bool is_palindrome(BidirectionalIterator begin, BidirectionalIterator end)
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{
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if(begin == end)
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{
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return true;
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}
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--end;
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while(begin != end)
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{
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if(!(*begin == *end))
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{
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return false;
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}
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++begin;
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if(begin == end)
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{
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break;
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}
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--end;
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}
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return true;
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}
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/// \fn is_palindrome ( const R& range )
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/// \return true if the entire sequence is palindrome
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///
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/// \param range The range to be tested.
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///
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/// \note This function will return true for empty sequences and for palindromes.
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/// For other sequences function will return false.
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/// Complexity: O(N).
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template <typename R>
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bool is_palindrome(const R& range)
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{
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return is_palindrome(boost::begin(range), boost::end(range));
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}
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/// \fn is_palindrome ( const R& range, Predicate p )
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/// \return true if the entire sequence is palindrome
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///
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/// \param range The range to be tested.
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/// \param p A predicate used to compare the values.
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///
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/// \note This function will return true for empty sequences and for palindromes.
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/// For other sequences function will return false.
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/// Complexity: O(N).
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template <typename R, typename Predicate>
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bool is_palindrome(const R& range, Predicate p)
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{
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return is_palindrome(boost::begin(range), boost::end(range), p);
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}
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/// \fn is_palindrome ( const char* str )
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/// \return true if the entire sequence is palindrome
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///
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/// \param str C-string to be tested.
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///
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/// \note This function will return true for empty sequences and for palindromes.
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/// For other sequences function will return false.
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/// Complexity: O(N).
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bool is_palindrome(const char* str)
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{
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if(!str)
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return true;
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return is_palindrome(str, str + strlen(str));
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}
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/// \fn is_palindrome ( const char* str, Predicate p )
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/// \return true if the entire sequence is palindrome
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///
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/// \param str C-string to be tested.
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/// \param p A predicate used to compare the values.
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///
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/// \note This function will return true for empty sequences and for palindromes.
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/// For other sequences function will return false.
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/// Complexity: O(N).
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template<typename Predicate>
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bool is_palindrome(const char* str, Predicate p)
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{
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if(!str)
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return true;
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return is_palindrome(str, str + strlen(str), p);
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}
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}}
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#endif // BOOST_ALGORITHM_IS_PALINDROME_HPP
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