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std::find_end(3)	       C++ Standard Libary		std::find_end(3)

NAME
     std::find_end - std::find_end

Synopsis
	Defined in header <algorithm>
	template< class ForwardIt1, class ForwardIt2 >

	ForwardIt1  find_end( ForwardIt1 first, ForwardIt1 last,  (1) (constexpr
     since C++20)

			     ForwardIt2 s_first, ForwardIt2
	s_last );
	template< class ExecutionPolicy, class ForwardIt1, class
	ForwardIt2 >

	ForwardIt1  find_end(  ExecutionPolicy&&  policy,	     (2)  (since
     C++17)
			     ForwardIt1 first, ForwardIt1 last,

			     ForwardIt2 s_first, ForwardIt2
	s_last );
	template< class ForwardIt1, class ForwardIt2, class
	BinaryPred >

	ForwardIt1  find_end( ForwardIt1 first, ForwardIt1 last,  (3) (constexpr
     since C++20)
			     ForwardIt2 s_first, ForwardIt2
	s_last,

			     BinaryPred p );
	template< class ExecutionPolicy,

		  class ForwardIt1, class ForwardIt2, class
	BinaryPred >
	ForwardIt1  find_end(  ExecutionPolicy&&  policy,	     (4)  (since
     C++17)
			     ForwardIt1 first, ForwardIt1 last,
			     ForwardIt2 s_first, ForwardIt2
	s_last,

			     BinaryPred p );

	Searches  for  the  last occurrence of the sequence [s_first, s_last) in
     the range
	[first, last).

	1) Elements are compared using operator==.
	3) Elements are compared using the given binary predicate p.
	2,4) Same as (1,3), but executed according to policy.
	These overloads participate in overload resolution only if

	std::is_execution_policy_v<std::decay_t<ExecutionPolicy>>    is    true.
     (until
										  C++20)
	std::is_execution_policy_v<std::remove_cvref_t<ExecutionPolicy>>      is
     true. (since
										  C++20)

Parameters
	first, last	- the range of elements to examine
	s_first, s_last - the range of elements to search for
	policy		- the execution policy to use. See execution policy  for
     details.
			  binary  predicate  which  returns true if the elements
     should be
			  treated as equal.

			  The signature of  the  predicate  function  should  be
     equivalent to
			  the following:

			   bool pred(const Type1 &a, const Type2 &b);

	p		- While the signature does not need to have const &, the
     function
			  must	not  modify the objects passed to it and must be
     able to
			  accept all values of type (possibly const)  Type1  and
     Type2
			  regardless of value category (thus, Type1 & is not al-
     lowed
			  ,  nor  is Type1 unless for Type1 a move is equivalent
     to a copy
			  (since C++11)).
			  The types Type1 and Type2 must be such that objects of
     types
			  ForwardIt1 and ForwardIt2 can be dereferenced and then
     implicitly
			  converted to Type1 and Type2 respectively.

Type requirements
	-
	ForwardIt1 must meet the requirements of LegacyForwardIterator.
	-
	ForwardIt2 must meet the requirements of LegacyForwardIterator.

Return value
	Iterator to the beginning of last occurrence of the  sequence  [s_first,
     s_last) in
	range [first, last).

	If  [s_first,  s_last) is empty or if no such sequence is found, last is
     returned.

Complexity
	Given \(\scriptsize N\)N as std::distance(first1, last1) and  \(\script-
     size S\)S as
	std::distance(first2, last2):

	1,2)  At  most \(\scriptsize S\cdot(N-S+1)\)SA.(N-S+1) comparisons using
     operator==.
	3,4) At most \(\scriptsize S\cdot(N-S+1)\)SA.(N-S+1) applications of the
     predicate p.

Exceptions
	The overloads with a template parameter named ExecutionPolicy report er-
     rors as
	follows:

	  * If execution of a function invoked as part of the  algorithm  throws
     an exception
	    and  ExecutionPolicy is one of the standard policies, std::terminate
     is called.
	    For any other ExecutionPolicy, the	behavior  is  implementation-de-
     fined.
	  * If the algorithm fails to allocate memory, std::bad_alloc is thrown.

Possible implementation
					find_end (1)
	template<class ForwardIt1, class ForwardIt2>
	constexpr //< since C++20
	ForwardIt1 find_end(ForwardIt1 first, ForwardIt1 last,
			    ForwardIt2 s_first, ForwardIt2 s_last)
	{
	    if (s_first == s_last)
		return last;

	    ForwardIt1 result = last;
	    while (true)
	    {
		ForwardIt1   new_result   =  std::search(first,  last,	s_first,
     s_last);
		if (new_result == last)
		    break;
		else
		{
		    result = new_result;
		    first = result;
		    ++first;
		}
	    }
	    return result;
	}
					find_end (3)
	template<class ForwardIt1, class ForwardIt2, class BinaryPred>
	constexpr //< since C++20
	ForwardIt1 find_end(ForwardIt1 first, ForwardIt1 last,
			    ForwardIt2 s_first, ForwardIt2 s_last,
			    BinaryPred p)
	{
	    if (s_first == s_last)
		return last;

	    ForwardIt1 result = last;
	    while (true)
	    {
		ForwardIt1  new_result	=  std::search(first,	last,	s_first,
     s_last, p);
		if (new_result == last)
		    break;
		else
		{
		    result = new_result;
		    first = result;
		    ++first;
		}
	    }
	    return result;
	}

Example
     // Run this code

      #include <algorithm>
      #include <array>
      #include <cmath>
      #include <iostream>

      auto print_result = [](auto result, const auto& v)
      {
	  result == v.end()
	      ? std::cout << "Sequence not found\n"
	      :  std::cout  <<	"Last occurrence is at: " << std::distance(v.be-
     gin(), result)
			  << '\n';
      };

      int main()
      {
	  const auto v = {1, 2, 3, 4, 1, 2, 3, 4, 1, 2, 3, 4};

	  for (auto const& x : {std::array{1, 2, 3}, {4, 5, 6}})
	  {
	      auto iter = std::find_end(v.begin(), v.end(), x.begin(), x.end());
     // overload (1)
	      print_result(iter, v);
	  }

	  for (auto const& x : {std::array{-1, -2, -3}, {-4, -5, -6}})
	  {
	      auto iter = std::find_end(v.begin(), v.end(), x.begin(),	x.end(),
     // overload (3)
					[](int x, int y)
					{
					    return std::abs(x) == std::abs(y);
					});
	      print_result(iter, v);
	  }
      }

Output:
      Last occurrence is at: 8
      Sequence not found
      Last occurrence is at: 8
      Sequence not found

	Defect reports

	The  following	behavior-changing  defect  reports were applied retroac-
     tively to
	previously published C++ standards.

	   DR	 Applied to	       Behavior as  published		    Cor-
     rect behavior
	LWG  1205 C++98      the return value was unclear if		 returns
     last in this
			    [s_first, s_last) is empty			case
	LWG 2150 C++98	    the condition of  asequence  occurencea  was    cor-
     rected
			    incorrect

See also
	search		 searches for a range of elements
			 (function template)
	includes	  returns  true  if one sequence is a subsequence of an-
     other
			 (function template)
			 finds the first two adjacent items that are  equal  (or
     satisfy a
	adjacent_find	 given predicate)
			 (function template)
	find
	find_if 	 finds the first element satisfying specific criteria
	find_if_not	 (function template)
	(C++11)
	find_first_of	 searches for any one of a set of elements
			 (function template)
	search_n	  searches a range for a number of consecutive copies of
     an element
			 (function template)
	ranges::find_end finds the last sequence of elements in a certain range
	(C++20) 	 (niebloid)

http://cppreference.com 	   2024.06.10			std::find_end(3)
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