algorithm.h

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/* *****************************************************************************
 * kblib is a general utility library for C++14 and C++17, intended to provide
 * performant high-level abstractions and more expressive ways to do simple
 * things.
 *
 * Copyright (c) 2021 killerbee
 *
 * 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 <https://www.gnu.org/licenses/>.
 * ****************************************************************************/
 
#ifndef ALGORITHM_H
#define ALGORITHM_H
 
#include "tdecl.h"
 
#include "iterators.h"
#include "traits.h"
 
#include <algorithm>
#include <cmath>
#include <tuple>
 
namespace KBLIB_NS {
 
template <typename Callable>
constexpr auto repeat(std::size_t N, Callable func) noexcept(noexcept(func()))
    -> return_assert_t<is_invocable<Callable>::value, void> {
   for (std::size_t I = 0; I != N; ++I) {
      func();
   }
   return;
}
 
template <typename Container, typename Elem>
constexpr auto erase(Container& c, const Elem& val) noexcept(
    noexcept(c.erase(std::remove(c.begin(), c.end(), val), c.end()))) -> void {
   c.erase(std::remove(c.begin(), c.end(), val), c.end());
   return;
}
 
template <typename Container, typename UnaryPredicate>
constexpr auto erase_if(Container& c, UnaryPredicate p) noexcept(
    noexcept(c.erase(std::remove_if(c.begin(), c.end(), std::ref(p)), c.end())))
    -> void {
   c.erase(std::remove_if(c.begin(), c.end(), std::ref(p)), c.end());
   return;
}
 
template <typename Obj>
KBLIB_NODISCARD constexpr auto equals(const Obj& a,
                                      const Obj& b) noexcept(noexcept(a < b))
    -> bool {
   return not (a < b) and not (b < a);
}
 
template <typename Obj, typename Compare>
KBLIB_NODISCARD constexpr auto equals(const Obj& a, const Obj& b,
                                      Compare comp) noexcept(noexcept(comp(a,
                                                                           b)))
    -> bool {
   return not comp(a, b) and not comp(b, a);
}
 
template <typename Compare = void, typename Obj = void>
struct equivalent {
   KBLIB_NODISCARD constexpr auto operator()(const Obj& a, const Obj& b,
                                             Compare comp) const
       noexcept(noexcept(equals(a, b, comp))) -> bool {
      return equals(a, b, comp);
   }
};
 
template <typename Obj>
struct equivalent<void, Obj> {
   KBLIB_NODISCARD constexpr auto operator()(const Obj& a, const Obj& b) const
       noexcept(noexcept(equals(a, b))) -> bool {
      return equals(a, b);
   }
};
 
template <typename Compare>
struct equivalent<Compare, void> {
   template <typename Obj>
   KBLIB_NODISCARD constexpr auto operator()(const Obj& a, const Obj& b,
                                             Compare comp) const
       noexcept(noexcept(equals(a, b, comp))) -> bool {
      return equals(a, b, comp);
   }
};
 
template <>
struct equivalent<void, void> {
   template <typename Obj>
   KBLIB_NODISCARD constexpr auto operator()(const Obj& a, const Obj& b) const
       noexcept(noexcept(equals(a, b))) -> bool {
      return equals(a, b);
   }
};
 
template <typename InputIt, typename T>
KBLIB_NODISCARD constexpr auto accumulate(InputIt first, InputIt last, T init)
    -> T {
   for (; first != last; ++first) {
      init = std::move(init) + *first;
   }
   return init;
}
 
template <class InputIt, class T, class BinaryOperation>
KBLIB_NODISCARD constexpr auto accumulate(InputIt first, InputIt last, T init,
                                          BinaryOperation op) -> T {
   for (; first != last; ++first) {
      init = op(std::move(init), *first);
   }
   return init;
}
 
template <typename InputIt>
KBLIB_NODISCARD constexpr auto sum(InputIt first, InputIt last)
    -> std::decay_t<decltype(*first)> {
   if (first == last) {
      return {};
   }
   auto init = *first++;
   return kblib::accumulate(first, last, std::move(init));
}
 
template <typename InputIt, typename BinaryOperation>
KBLIB_NODISCARD constexpr auto sum(InputIt first, InputIt last,
                                   BinaryOperation op)
    -> std::decay_t<decltype(*first)> {
   if (first == last) {
      return {};
   }
   auto init = *first++;
   return kblib::accumulate(first, last, std::move(init), op);
}
 
template <typename Range>
KBLIB_NODISCARD constexpr auto sum(Range&& r) -> auto {
   using std::begin;
   using std::end;
   auto first = begin(r);
   auto last = end(r);
   if (first == last) {
      return std::decay_t<decltype(*first)>{};
   }
   auto init = *first++;
   return kblib::accumulate(first, last, std::move(init));
}
 
template <typename InputIt, typename EndIt, typename OutputIt, typename T,
          typename BinaryAccumulation, typename UnaryTransform>
constexpr auto transform_exclusive_scan(InputIt first, EndIt last,
                                        OutputIt d_first, T init,
                                        BinaryAccumulation accum,
                                        UnaryTransform proj) -> OutputIt {
   while (first != last) {
      *d_first++
          = kblib::exchange(init, accum(std::move(init), proj(*first++)));
   }
   return d_first;
}
 
#if 0
template <typename InputIt, typename BinaryAccumulation,
          typename BinaryTransform>
KBLIB_NODISCARD constexpr auto
adjacent_reduce(InputIt begin, InputIt begin1, InputIt end,
                BinaryAccumulation acc, BinaryTransform op) {}
 
template <typename InputIt, typename BinaryTransform>
KBLIB_NODISCARD constexpr auto adjacent_transform(InputIt begin, InputIt begin1,
                                                  InputIt end,
                                                  BinaryTransform op) {}
 
template <typename InputIt, typename BinaryAccumulation,
          typename BinaryTransform>
KBLIB_NODISCARD constexpr auto
adjacent_inclusive_scan(InputIt begin, InputIt begin1, InputIt end,
                        BinaryAccumulation acc, BinaryTransform op) {}
#endif
 
template <typename ForwardIt, typename EndIt, typename Elem>
KBLIB_NODISCARD constexpr auto find(
    ForwardIt begin, EndIt end,
    const Elem& value) noexcept(noexcept(*begin == value)) -> ForwardIt {
   while (begin != end and *begin != value) {
      ++begin;
   }
   return begin;
}
 
template <typename ForwardIt, typename EndIt, typename Elem, typename Comp>
KBLIB_NODISCARD constexpr auto find(
    ForwardIt begin, EndIt end, const Elem& value,
    Comp&& comp) noexcept(noexcept(comp(*begin, value))) -> ForwardIt {
   while (begin != end and not equals(*begin, value, comp)) {
      ++begin;
   }
   return begin;
}
 
template <typename ForwardIt, typename EndIt, typename UnaryPredicate>
KBLIB_NODISCARD constexpr auto find_if(
    ForwardIt begin, EndIt end,
    UnaryPredicate&& pred) noexcept(noexcept(kblib::invoke(pred, *begin)))
    -> ForwardIt {
   while (begin != end and not kblib::invoke(pred, *begin)) {
      ++begin;
   }
   return begin;
}
 
template <typename ForwardIt, typename EndIt, typename UnaryPredicate>
KBLIB_NODISCARD constexpr auto find_if_not(
    ForwardIt begin, EndIt end,
    UnaryPredicate&& pred) noexcept(noexcept(kblib::invoke(pred, *begin)))
    -> ForwardIt {
   while (begin != end and kblib::invoke(pred, *begin)) {
      ++begin;
   }
   return begin;
}
 
template <typename ForwardIt, typename EndIt, typename Elem>
KBLIB_NODISCARD constexpr auto find_last(
    ForwardIt begin, EndIt end,
    const Elem& value) noexcept(noexcept(*begin == value)) -> ForwardIt {
   if (begin == end) {
      return begin;
   }
   auto result = end;
   while (true) {
      auto new_result = kblib::find(begin, end, value);
      if (new_result == end) {
         break;
      } else {
         result = new_result;
         begin = result;
         ++begin;
      }
   }
   return result;
}
 
template <typename ForwardIt, typename EndIt, typename UnaryPredicate>
KBLIB_NODISCARD constexpr auto find_last_if(
    ForwardIt begin, EndIt end,
    UnaryPredicate pred) noexcept(noexcept(kblib::invoke(pred, *begin)))
    -> ForwardIt {
   if (begin == end) {
      return begin;
   }
   auto result = end;
   while (true) {
      auto new_result = kblib::find_if(begin, end, pred);
      if (new_result == end) {
         break;
      } else {
         result = new_result;
         begin = result;
         ++begin;
      }
   }
   return result;
}
 
template <typename ForwardIt, typename EndIt, typename UnaryPredicate>
KBLIB_NODISCARD constexpr auto find_last_if_not(
    ForwardIt begin, EndIt end,
    UnaryPredicate pred) noexcept(noexcept(kblib::invoke(pred, *begin)))
    -> ForwardIt {
   if (begin == end) {
      return begin;
   }
   auto result = end;
   while (true) {
      auto new_result = kblib::find_if_not(begin, end, pred);
      if (new_result == end) {
         break;
      } else {
         result = new_result;
         begin = result;
         ++begin;
      }
   }
   return result;
}
 
template <typename ForwardIt, typename EndIt, typename Elem>
KBLIB_NODISCARD constexpr auto find_in(
    ForwardIt begin, EndIt end,
    const Elem& value) noexcept(noexcept(*begin == value)) -> size_t {
   return to_unsigned(kblib::find(begin, end, value) - begin);
}
 
template <typename ForwardIt, typename EndIt, typename UnaryPredicate>
KBLIB_NODISCARD constexpr auto find_in_if(
    ForwardIt begin, EndIt end,
    UnaryPredicate pred) noexcept(noexcept(kblib::invoke(pred, *begin)))
    -> size_t {
   return to_unsigned(kblib::find_if(begin, end, pred) - begin);
}
template <typename ForwardIt, typename EndIt, typename UnaryPredicate>
KBLIB_NODISCARD constexpr auto find_in_if_not(
    ForwardIt begin, EndIt end,
    UnaryPredicate pred) noexcept(noexcept(kblib::invoke(pred, *begin)))
    -> size_t {
   return to_unsigned(kblib::find_if_not(begin, end, pred) - begin);
}
 
// find_last_in:
// 1. Finds last v in range [begin, end) and returns the offset from begin
 
template <typename ForwardIt, typename EndIt, typename Elem>
KBLIB_NODISCARD constexpr auto find_last_in(
    ForwardIt begin, EndIt end,
    const Elem& value) noexcept(noexcept(*begin == value)) -> size_t {
   return to_unsigned(kblib::find_last(begin, end, value) - begin);
}
 
template <typename ForwardIt, typename EndIt, typename UnaryPredicate>
KBLIB_NODISCARD constexpr auto find_last_in_if(
    ForwardIt begin, EndIt end,
    UnaryPredicate pred) noexcept(noexcept(kblib::invoke(pred, *begin)))
    -> size_t {
   return to_unsigned(kblib::find_last_if(begin, end, pred) - begin);
}
template <typename ForwardIt, typename EndIt, typename UnaryPredicate>
KBLIB_NODISCARD constexpr auto find_last_in_if_not(
    ForwardIt begin, EndIt end,
    UnaryPredicate pred) noexcept(noexcept(kblib::invoke(pred, *begin)))
    -> size_t {
   return to_unsigned(kblib::find_last_if_not(begin, end, pred) - begin);
}
 
template <typename Container, typename T>
KBLIB_NODISCARD constexpr auto
find_in(const Container& c, const T& value) noexcept(
    noexcept(*std::declval<iterator_type_for_t<const Container>&>() == value))
    -> size_t {
   using std::begin;
   using std::end;
   return to_unsigned(kblib::find(begin(c), end(c), value) - begin(c));
}
#if 0
template<typename ExecutionPolicy, typename Container, typename T>
KBLIB_NODISCARD constexpr auto find_in(ExecutionPolicy&& policy,
                                         const Container& c, const T& v) -> size_t {
  return to_unsigned(std::find(policy, std::begin(c), std::end(c), v) - std::begin(c));
}
#endif
 
template <typename Container, typename UnaryPredicate>
KBLIB_NODISCARD constexpr auto find_in_if(
    const Container& c,
    UnaryPredicate
        pred) noexcept(noexcept(kblib::invoke(pred,
                                              *std::declval<iterator_type_for_t<
                                                  const Container>&>())))
    -> size_t {
   using std::begin;
   using std::end;
   return to_unsigned(kblib::find_if(begin(c), end(c), pred) - begin(c));
}
template <typename Container, typename UnaryPredicate>
KBLIB_NODISCARD constexpr auto find_in_if_not(
    const Container& c,
    UnaryPredicate
        pred) noexcept(noexcept(kblib::invoke(pred,
                                              *std::declval<iterator_type_for_t<
                                                  const Container>&>())))
    -> size_t {
   using std::begin;
   using std::end;
   return to_unsigned(kblib::find_if_not(begin(c), end(c), pred) - begin(c));
}
#if 0
template<typename ExecutionPolicy, typename Container, typename UnaryPredicate>
KBLIB_NODISCARD constexpr auto find_in_if(ExecutionPolicy&& policy,
                                            const Container& c,
                                            UnaryPredicate p) -> size_t {
  return std::find_if(policy, std::begin(c), std::end(c), p) - std::begin(c);
}
template<typename ExecutionPolicy, typename Container, typename UnaryPredicate>
KBLIB_NODISCARD constexpr auto find_in_if_not(ExecutionPolicy&& policy,
                                                const Container& c,
                                                UnaryPredicate p) -> size_t {
  return std::find_if_not(policy, std::begin(c), std::end(c), p)
        - std::begin(c);
}
#endif
 
template <typename Container, typename T>
KBLIB_NODISCARD constexpr auto
find_last_in(const Container& c, const T& value) noexcept(
    noexcept(*std::declval<iterator_type_for_t<const Container>&>() == value))
    -> size_t {
   using std::begin;
   using std::end;
   return to_unsigned(kblib::find_last(begin(c), end(c), value) - begin(c));
}
 
template <typename Container, typename UnaryPredicate>
KBLIB_NODISCARD constexpr auto find_last_in_if(
    const Container& c,
    UnaryPredicate
        pred) noexcept(noexcept(kblib::invoke(pred,
                                              *std::declval<iterator_type_for_t<
                                                  const Container>&>())))
    -> size_t {
   using std::begin;
   using std::end;
   return to_unsigned(kblib::find_last_if(begin(c), end(c), pred) - begin(c));
}
template <typename Container, typename UnaryPredicate>
KBLIB_NODISCARD constexpr auto find_last_in_if_not(
    const Container& c,
    UnaryPredicate
        pred) noexcept(noexcept(kblib::invoke(pred,
                                              *std::declval<iterator_type_for_t<
                                                  const Container>&>())))
    -> size_t {
   using std::begin;
   using std::end;
   return to_unsigned(kblib::find_last_if_not(begin(c), end(c), pred)
                      - begin(c));
}
 
template <typename InputIt1, typename EndIt1, typename InputIt2,
          typename BinaryPredicate = std::equal_to<>>
KBLIB_NODISCARD constexpr auto find_match(InputIt1 begin1, EndIt1 end1,
                                          InputIt2 begin2, BinaryPredicate cmp)
    -> enable_if_t<is_input_iterator<InputIt1>::value
                       and is_input_iterator<InputIt2>::value
                       and is_invocable<BinaryPredicate, decltype(*begin1),
                                        decltype(*begin2)>::value,
                   std::pair<InputIt1, InputIt2>> {
   while (begin1 != end1) {
      if (kblib::invoke(cmp, *begin1++, *begin2++)) {
         return std::make_pair(begin1, begin2);
      }
   }
   return std::make_pair(begin1, begin2);
}
template <typename InputIt1, typename EndIt1, typename InputIt2,
          typename EndIt2, typename BinaryPredicate = std::equal_to<>>
KBLIB_NODISCARD constexpr auto find_match(InputIt1 begin1, EndIt1 end1,
                                          InputIt2 begin2, EndIt2 end2,
                                          BinaryPredicate cmp)
    -> enable_if_t<is_input_iterator<InputIt1>::value
                       and is_input_iterator<InputIt2>::value
                       and is_invocable<BinaryPredicate, decltype(*begin1),
                                        decltype(*begin2)>::value,
                   std::pair<InputIt1, InputIt2>> {
   while (begin1 != end1 and begin2 != end2) {
      if (kblib::invoke(cmp, *begin1++, *begin2++)) {
         return std::make_pair(begin1, begin2);
      }
   }
   return std::make_pair(begin1, begin2);
}
 
template <typename InputIt1, typename EndIt1, typename InputIt2,
          typename EndIt2, typename BinaryPred>
KBLIB_NODISCARD constexpr auto starts_with(InputIt1 begin1, EndIt1 end1,
                                           InputIt2 begin2, EndIt2 end2,
                                           BinaryPred pred)
    -> enable_if_t<
        (is_input_iterator_v<InputIt1> and is_input_iterator_v<InputIt2>) //
        and not (is_random_access_iterator_v<
                     InputIt1> and is_random_access_iterator_v<InputIt2>),
        bool> {
   while (begin1 != end1 and begin2 != end2) {
      if (not kblib::invoke(pred, *begin1++, *begin2++)) {
         return false;
      }
   }
   return begin2 == end2;
}
 
template <typename RandomAccessIt1, typename RandomAccessIt2,
          typename BinaryPred = std::equal_to<>>
KBLIB_NODISCARD constexpr auto starts_with(RandomAccessIt1 begin1,
                                           RandomAccessIt1 end1,
                                           RandomAccessIt2 begin2,
                                           RandomAccessIt2 end2,
                                           BinaryPred pred = {})
    -> enable_if_t<
        is_random_access_iterator_v<
            RandomAccessIt1> and is_random_access_iterator_v<RandomAccessIt2>,
        bool> {
   if (end2 - begin2 > end1 - begin1) {
      return false;
   } else {
      auto N = end2 - begin2;
      return kblib::equal(begin1, begin1 + N, begin2, pred);
   }
}
 
template <typename BidirIt1, typename BidirIt2,
          typename BinaryPred = std::equal_to<>>
KBLIB_NODISCARD constexpr auto ends_with(BidirIt1 begin1, BidirIt1 end1,
                                         BidirIt2 begin2, BidirIt2 end2,
                                         BinaryPred pred = {})
    -> enable_if_t<
        (is_bidirectional_iterator_v<BidirIt1>      //
         and is_bidirectional_iterator_v<BidirIt2>) //
        and not (is_random_access_iterator_v<
                     BidirIt1> and is_random_access_iterator_v<BidirIt2>),
        bool> {
   while (begin1 != end1 and begin2 != end2) {
      if (not kblib::invoke(pred, *--end1, *--end2)) {
         return false;
      }
   }
   return begin2 == end2;
}
 
template <typename RandomAccessIt1, typename RandomAccessIt2,
          typename BinaryPred = std::equal_to<>>
KBLIB_NODISCARD constexpr auto ends_with(RandomAccessIt1 begin1,
                                         RandomAccessIt1 end1,
                                         RandomAccessIt2 begin2,
                                         RandomAccessIt2 end2,
                                         BinaryPred pred = {})
    -> enable_if_t<
        is_random_access_iterator_v<
            RandomAccessIt1> and is_random_access_iterator_v<RandomAccessIt2>,
        bool> {
   if (end2 - begin2 > end1 - begin1) {
      return false;
   } else {
      auto N = end2 - begin2;
      return kblib::equal(end1 - N, end1, begin2, pred);
   }
}
 
template <typename InputIt, typename EndIt, typename T, typename UnaryTransform>
KBLIB_NODISCARD constexpr auto first_result(InputIt begin, EndIt end, T def,
                                            UnaryTransform op)
    -> enable_if_t<is_input_iterator<InputIt>::value,
                   std::decay_t<decltype(op(*begin))>> {
   for (; begin != end; ++begin) {
      auto cur = op(*begin);
      if (cur != def) {
         return cur;
      }
   }
   return def;
}
template <typename InputIt1, typename EndIt1, typename InputIt2, typename T,
          typename BinaryTransform>
KBLIB_NODISCARD constexpr auto first_result(InputIt1 begin1, EndIt1 end1,
                                            InputIt2 begin2, T def,
                                            BinaryTransform op)
    -> enable_if_t<is_input_iterator<InputIt1>::value
                       and is_input_iterator<InputIt2>::value,
                   std::decay_t<decltype(op(*begin1, *begin2))>> {
   for (; begin1 != end1; ++begin1, ++begin2) {
      auto cur = op(*begin1, *begin2);
      if (cur != def) {
         return cur;
      }
   }
   return def;
}
template <typename InputIt1, typename EndIt1, typename InputIt2,
          typename EndIt2, typename T, typename BinaryTransform>
KBLIB_NODISCARD constexpr auto first_result(InputIt1 begin1, EndIt1 end1,
                                            InputIt2 begin2, EndIt2 end2, T def,
                                            BinaryTransform op)
    -> enable_if_t<is_input_iterator<InputIt1>::value
                       and is_input_iterator<InputIt2>::value,
                   std::decay_t<decltype(op(*begin1, *begin2))>> {
   for (; begin1 != end1 and begin2 != end2; ++begin1, ++begin2) {
      auto cur = op(*begin1, *begin2);
      if (cur != def) {
         return cur;
      }
   }
   return def;
}
 
template <typename InputIt, typename EndIt, typename T, typename UnaryTransform,
          typename UnaryPredicate>
KBLIB_NODISCARD constexpr auto first_result_if(InputIt begin, EndIt end, T def,
                                               UnaryTransform op,
                                               UnaryPredicate ch)
    -> enable_if_t<is_input_iterator<InputIt>::value, decltype(op(*begin))> {
   for (; begin != end; ++begin) {
      if (ch(*begin)) {
         return op(*begin);
      }
   }
   return def;
}
template <typename InputIt1, typename EndIt1, typename InputIt2, typename T,
          typename BinaryTransform, typename BinaryPredicate>
KBLIB_NODISCARD constexpr auto first_result_if(InputIt1 begin1, EndIt1 end1,
                                               InputIt2 begin2, T def,
                                               BinaryTransform op,
                                               BinaryPredicate ch)
    -> enable_if_t<is_input_iterator<InputIt1>::value
                       and is_input_iterator<InputIt2>::value,
                   decltype(op(*begin1, *begin2))> {
   for (; begin1 != end1; ++begin1, ++begin2) {
      if (ch(*begin1, *begin2)) {
         return op(*begin1, *begin2);
      }
   }
   return def;
}
template <typename InputIt1, typename EndIt1, typename InputIt2,
          typename EndIt2, typename T, typename BinaryTransform,
          typename BinaryPredicate>
KBLIB_NODISCARD constexpr auto first_result_if(InputIt1 begin1, EndIt1 end1,
                                               InputIt2 begin2, EndIt2 end2,
                                               T def, BinaryTransform op,
                                               BinaryPredicate ch)
    -> enable_if_t<is_input_iterator<InputIt1>::value
                       and is_input_iterator<InputIt2>::value,
                   decltype(op(*begin1, *begin2))> {
   for (; begin1 != end1 and begin2 != end2; ++begin1, ++begin2) {
      if (ch(*begin1, *begin2)) {
         return op(*begin1, *begin2);
      }
   }
   return def;
}
 
#if KBLIB_USE_CXX17
template <typename T>
struct is_optional : std::false_type {};
template <typename U>
struct is_optional<std::optional<U>> : std::true_type {};
 
template <typename InputIt, typename EndIt, typename T, typename UnaryTransform>
KBLIB_NODISCARD constexpr auto first_result_opt(InputIt begin, EndIt end, T def,
                                                UnaryTransform op)
    -> enable_if_t<is_input_iterator<InputIt>::value,
                   std::decay_t<decltype(op(*begin))>> {
   for (; begin != end; ++begin) {
      auto cur = op(*begin);
      if (cur) {
         return cur;
      }
   }
   return def;
}
template <typename InputIt1, typename EndIt1, typename InputIt2, typename T,
          typename BinaryTransform>
KBLIB_NODISCARD constexpr auto first_result_opt(InputIt1 begin1, EndIt1 end1,
                                                InputIt2 begin2, T def,
                                                BinaryTransform op)
    -> enable_if_t<is_input_iterator<InputIt1>::value
                       and is_input_iterator<InputIt2>::value,
                   std::decay_t<decltype(op(*begin1, *begin2))>> {
   for (; begin1 != end1; ++begin1, ++begin2) {
      auto cur = op(*begin1, *begin2);
      if (cur) {
         return cur;
      }
   }
   return def;
}
template <typename InputIt1, typename EndIt1, typename InputIt2,
          typename EndIt2, typename T, typename BinaryTransform>
KBLIB_NODISCARD constexpr auto first_result_opt(InputIt1 begin1, EndIt1 end1,
                                                InputIt2 begin2, EndIt2 end2,
                                                T def, BinaryTransform op)
    -> enable_if_t<is_input_iterator<InputIt1>::value
                       and is_input_iterator<InputIt2>::value,
                   std::decay_t<decltype(op(*begin1, *begin2))>> {
   for (; begin1 != end1 and begin2 != end2; ++begin1, ++begin2) {
      auto cur = op(*begin1, *begin2);
      if (cur) {
         return cur;
      }
   }
   return def;
}
#endif
 
template <typename InputIt, typename UnaryPredicate>
KBLIB_NODISCARD constexpr auto all_of(InputIt begin, InputIt end,
                                      UnaryPredicate pred)
    -> enable_if_t<is_input_iterator<InputIt>::value, bool> {
   for (; begin != end; ++begin) {
      if (not kblib::invoke(pred, *begin)) {
         return false;
      }
   }
   return true;
}
template <typename Range, typename UnaryPredicate>
KBLIB_NODISCARD constexpr auto all_of(Range&& rng, UnaryPredicate pred)
    -> enable_if_t<is_iterable<Range>::value, bool> {
   for (auto&& el : std::forward<Range>(rng)) {
      if (not kblib::invoke(pred, static_cast<decltype(el)>(el))) {
         return false;
      }
   }
   return true;
}
template <typename InputIt, typename UnaryPredicate>
KBLIB_NODISCARD constexpr auto none_of(InputIt begin, InputIt end,
                                       UnaryPredicate pred)
    -> enable_if_t<is_input_iterator<InputIt>::value, bool> {
   for (; begin != end; ++begin) {
      if (kblib::invoke(pred, *begin)) {
         return false;
      }
   }
   return true;
}
template <typename Range, typename UnaryPredicate>
KBLIB_NODISCARD constexpr auto none_of(Range&& rng, UnaryPredicate pred)
    -> enable_if_t<is_iterable<Range>::value, bool> {
   for (auto&& el : std::forward<Range>(rng)) {
      if (kblib::invoke(pred, static_cast<decltype(el)>(el))) {
         return false;
      }
   }
   return true;
}
template <typename InputIt, typename UnaryPredicate>
KBLIB_NODISCARD constexpr auto any_of(InputIt begin, InputIt end,
                                      UnaryPredicate pred)
    -> enable_if_t<is_input_iterator<InputIt>::value, bool> {
   for (; begin != end; ++begin) {
      if (kblib::invoke(pred, *begin)) {
         return true;
      }
   }
   return false;
}
template <typename Range, typename UnaryPredicate>
KBLIB_NODISCARD constexpr auto any_of(Range&& rng, UnaryPredicate pred)
    -> enable_if_t<is_iterable<Range>::value, bool> {
   for (auto&& el : std::forward<Range>(rng)) {
      if (kblib::invoke(pred, static_cast<decltype(el)>(el))) {
         return true;
      }
   }
   return false;
}
 
template <typename InputIt, typename Value>
KBLIB_NODISCARD constexpr auto contains(
    InputIt begin, InputIt end,
    const Value& val) noexcept(noexcept(*begin == val))
    -> enable_if_t<is_input_iterator<InputIt>::value, bool> {
   return kblib::any_of(begin, end, [&](const auto& e) { return e == val; });
}
 
template <typename Set, typename Value>
KBLIB_NODISCARD constexpr auto contains(
    const Set& set,
    const Value&
        val) noexcept(noexcept(*std::declval<iterator_type_for_t<const Set>&>()
                               == val))
    -> enable_if_t<is_iterable<Set>::value, bool> {
   using std::begin;
   using std::end;
   return kblib::any_of(begin(set), end(set),
                        [&](const auto& e) { return e == val; });
}
 
template <typename InputIt1, typename InputIt2>
KBLIB_NODISCARD constexpr auto contains_any(InputIt1 begin, InputIt1 end,
                                            InputIt2 n_begin, InputIt2 n_end)
    -> enable_if_t<is_input_iterator<InputIt1>::value
                       and is_input_iterator<InputIt2>::value,
                   bool> {
   return kblib::any_of(begin, end, [=](const auto& v) {
      return kblib::contains(n_begin, n_end, v);
   });
}
 
template <typename InputIt, typename Range2>
KBLIB_NODISCARD constexpr auto contains_any(InputIt begin, InputIt end,
                                            Range2&& needle)
    -> enable_if_t<is_input_iterator<InputIt>::value
                       and is_iterable<Range2>::value,
                   bool> {
   return kblib::any_of(begin, end, [&needle](const auto& v) {
      return kblib::contains(needle, v);
   });
}
 
template <typename Range1, typename Range2>
KBLIB_NODISCARD constexpr auto contains_any(Range1&& haystack, Range2&& needle)
    -> enable_if_t<is_iterable<Range1>::value and is_iterable<Range2>::value,
                   bool> {
   using std::begin;
   using std::end;
   return kblib::any_of(
       begin(haystack), end(haystack),
       [&needle](const auto& v) { return kblib::contains(needle, v); });
}
 
template <typename ForwardIt, typename EndIt, typename Compare = std::less<>>
constexpr auto max_element(ForwardIt first, EndIt last, Compare comp = {})
    -> ForwardIt {
   if (first == last) {
      return first;
   }
 
   ForwardIt largest = first;
   ++first;
   for (; first != last; ++first) {
      if (comp(*largest, *first)) {
         largest = first;
      }
   }
   return largest;
}
 
template <typename SequenceContainer, typename Comp = std::less<>, typename It,
          enable_if_t<is_linear_container_v<SequenceContainer>, int> = 0>
KBLIB_NODISCARD constexpr auto get_max_n_old(It first, It last,
                                             std::size_t count, Comp cmp = {})
    -> SequenceContainer {
   using std::begin;
   using std::end;
   assert(first + count <= last);
   SequenceContainer c{first, first + count};
   std::for_each(first + count, last, [&](const auto& v) {
      auto& min_v = *std::min_element(begin(c), end(c), cmp);
      if (kblib::invoke(cmp, min_v, v)) {
         min_v = v;
      }
   });
   return c;
}
 
template <typename SetlikeContainer, typename Comp = std::less<>, typename It,
          enable_if_t<is_setlike_v<SetlikeContainer>, int> = 0>
KBLIB_NODISCARD constexpr auto get_max_n_old(It first, It last,
                                             std::size_t count, Comp cmp = {})
    -> SetlikeContainer {
   auto temp = get_max_n_old<std::vector<key_type_setlike_t<SetlikeContainer>>>(
       first, last, count, cmp);
   return SetlikeContainer{std::make_move_iterator(temp.begin()),
                           std::make_move_iterator(temp.end())};
}
 
template <typename SequenceContainer, typename Comp = std::less<>, typename It,
          enable_if_t<is_linear_container_v<SequenceContainer>, int> = 0>
KBLIB_NODISCARD constexpr auto get_max_n(It first, It last, std::size_t count,
                                         Comp cmp = {}) -> SequenceContainer {
   using std::begin;
   using std::end;
   SequenceContainer c(count);
   std::partial_sort_copy(first, last, begin(c), end(c),
                          [&](auto&& a, auto&& b) -> decltype(auto) {
                             return kblib::invoke(cmp,
                                                  std::forward<decltype(b)>(b),
                                                  std::forward<decltype(a)>(a));
                          });
   return c;
}
 
template <typename SetlikeContainer, typename Comp = std::less<>, typename It,
          enable_if_t<is_setlike_v<SetlikeContainer>, int> = 0>
KBLIB_NODISCARD constexpr auto get_max_n(It first, It last, std::size_t count,
                                         Comp cmp = {}) -> SetlikeContainer {
   auto temp = get_max_n<std::vector<key_type_setlike_t<SetlikeContainer>>>(
       first, last, count, cmp);
   return SetlikeContainer{std::make_move_iterator(temp.begin()),
                           std::make_move_iterator(temp.end())};
}
 
template <typename Comp = std::less<>, typename InputIt, typename OutputIt,
          typename Elem = typename std::iterator_traits<InputIt>::value_type>
constexpr auto get_max_n(InputIt first, InputIt last, OutputIt d_begin,
                         std::size_t count, Comp cmp = {})
    -> return_assert_t<is_output_iterator_for<OutputIt, Elem>::value,
                       OutputIt> {
   auto temp = get_max_n<std::vector<Elem>>(first, last, count, cmp);
   return std::move(temp.begin(), temp.end(), d_begin);
}
 
template <typename ForwardIt, typename EndIt, typename ForwardIt2,
          typename BinaryFunction>
constexpr auto for_each(ForwardIt first, EndIt last, ForwardIt2 second,
                        BinaryFunction f) -> BinaryFunction {
   for (; first != last; (void)++first, (void)++second) {
      kblib::invoke(f, *first, *second);
   }
   return std::move(f);
}
 
template <typename ForwardIt, typename ForwardIt2, typename Size,
          typename BinaryFunction>
constexpr auto for_each_n(ForwardIt first, Size n, ForwardIt2 second,
                          BinaryFunction f)
    -> std::pair<ForwardIt, ForwardIt2> {
   for (Size i = 0; i < n; (void)++first, (void)++second, (void)++i) {
      kblib::invoke(f, *first, *second);
   }
   return {first, second};
}
 
template <typename InputIt, typename EndIt, typename OutputIt>
constexpr auto copy(InputIt first, EndIt last, OutputIt out) -> OutputIt {
   while (first != last) {
      *out++ = *first++;
   }
   return out;
}
 
template <typename InputIt, typename EndIt, typename OutputIt,
          typename UnaryPredicate>
constexpr auto copy_if(InputIt first, EndIt last, OutputIt out,
                       UnaryPredicate pred) -> OutputIt {
   while (first != last) {
      if (kblib::invoke(pred, *first)) {
         *out++ = *first;
      }
      first++;
   }
   return out;
}
 
template <typename InputIt, typename Size, typename OutputIt>
constexpr auto copy_n(InputIt first, Size count, OutputIt out) -> OutputIt {
   for (Size i = 0; i < count; ++i) {
      *out++ = *first++;
   }
   return out;
}
 
template <typename InputIt, typename Size, typename OutputIt,
          typename UnaryPredicate>
constexpr auto copy_n_if(InputIt first, Size count, OutputIt out,
                         UnaryPredicate pred) -> OutputIt {
   for (Size i = 0; i < count; ++i) {
      if (kblib::invoke(pred, *first)) {
         *out++ = *first;
      }
      ++first;
   }
   return out;
}
 
template <typename InputIt, typename EndIt, typename OutputIt,
          typename UnaryPredicate, typename T>
constexpr auto replace_copy_if(InputIt first, EndIt last, OutputIt out,
                               UnaryPredicate pred, const T& new_value)
    -> OutputIt {
   while (first != last) {
      if (kblib::invoke(pred, *first)) {
         *out = *first;
      } else {
         *out = new_value;
      }
      ++first;
      ++out;
   }
   return out;
}
 
template <typename InputIt, typename Size, typename OutputIt,
          typename UnaryPredicate, typename T>
constexpr auto replace_copy_n_if(InputIt first, Size count, OutputIt out,
                                 UnaryPredicate pred, const T& new_value)
    -> OutputIt {
   for (Size i = 0; i < count; ++i) {
      if (kblib::invoke(pred, *first)) {
         *out = *first;
      } else {
         *out = new_value;
      }
      ++first;
      ++out;
   }
   return out;
}
 
// TODO(killerbee13): Debug and test search_replace_copy
template <typename ForwardIt1, typename ForwardIt2, typename ForwardIt3,
          typename OutputIt, typename BinaryPredicate = std::equal_to<>>
constexpr auto search_replace_copy(ForwardIt1 h_begin, ForwardIt1 h_end,
                                   ForwardIt2 n_begin, ForwardIt2 n_end,
                                   ForwardIt3 r_begin, ForwardIt3 r_end,
                                   OutputIt d_begin,
                                   BinaryPredicate Compare = {}) -> OutputIt {
   if (n_begin == n_end) {
      return copy(h_begin, h_end, d_begin);
   } else {
      const auto needle_length = std::distance(n_begin, n_end);
      while (h_begin != h_end) {
         const auto found
             = std::search(h_begin, h_end, n_begin, n_end, Compare);
         d_begin = kblib::copy(h_begin, found, d_begin);
         h_begin = found;
         if (h_begin != h_end) {
            d_begin = copy(r_begin, r_end, d_begin);
            std::advance(h_begin, needle_length);
         }
      }
      return d_begin;
   }
}
 
template <typename Haystack, typename Needle, typename Replacement,
          typename OutputIt, typename BinaryPredicate = std::equal_to<>>
constexpr auto search_replace_copy(Haystack&& haystack, Needle&& needle,
                                   Replacement&& replacement, OutputIt d_begin,
                                   BinaryPredicate compare = {}) {
   using std::begin;
   using std::end;
   return search_replace_copy(begin(haystack), end(haystack),       //
                              begin(needle), end(needle),           //
                              begin(replacement), end(replacement), //
                              d_begin,                              //
                              compare);
}
 
template <class ForwardIt>
constexpr auto rotate(ForwardIt first, ForwardIt n_first,
                      ForwardIt last) noexcept(noexcept(swap(*first, *first)))
    -> ForwardIt {
   if (first == n_first)
      return last;
   if (n_first == last)
      return first;
 
   ForwardIt read = n_first;
   ForwardIt write = first;
   ForwardIt next_read = first; // read position for when "read" hits "last"
 
   while (read != last) {
      if (write == next_read)
         next_read = read; // track where "first" went
      // iter_swap is not constexpr
      // std::iter_swap(write++, read++);
      swap(*(write++), *(read++));
   }
 
   // rotate the remaining sequence into place
   kblib::rotate(write, next_read, last);
   return write;
}
 
template <typename OutputIt, typename EndIt, typename Generator>
constexpr auto generate(OutputIt first, EndIt last,
                        Generator g) noexcept(noexcept(*++first = g()))
    -> OutputIt {
   while (first != last) {
      *first = g();
      ++first;
   }
   return first;
}
 
template <typename OutputIt, typename Size, typename Generator>
constexpr auto generate_n(OutputIt first, Size count,
                          Generator g) noexcept(noexcept(*first++ = g()))
    -> OutputIt {
   for (Size i = 0; i < count; i++) {
      *first++ = g();
   }
   return first;
}
 
template <typename ForwardIt, typename T>
constexpr auto iota(ForwardIt first, ForwardIt last, T value) noexcept(
    noexcept(*first++ = value) and noexcept(++value)) -> void {
   while (first != last) {
      *first++ = value;
      ++value;
   }
}
 
// For some reason these long noexcept specifications really trip
// up clang-format
// clang-format off
template <typename ForwardIt, typename T, typename UnaryOperation>
constexpr auto iota(
    ForwardIt first, ForwardIt last, T value,
    UnaryOperation unary_op
   ) noexcept(noexcept(*first++ = value)
              and noexcept(kblib::invoke(unary_op,
                                         std::move(value))))
    -> void {
   // clang-format on
   while (first != last) {
      *first++ = value;
      value = kblib::invoke(unary_op, std::move(value));
   }
}
 
// clang-format off
template <typename InputIt, typename EndIt, typename... Params>
constexpr auto call_each(
    InputIt first, EndIt last, Params&&... params
   ) noexcept(noexcept(kblib::invoke(*first++,
                                     std::forward<Params>(params)...)))
    -> InputIt {
   // clang-format on
   while (first != last) {
      kblib::invoke(*first++, std::forward<Params>(params)...);
   }
   return first;
}
 
template <typename InputIt, typename EndIt, typename OutputIt,
          typename UnaryOperation>
constexpr auto transform(InputIt first, EndIt last, OutputIt d_first,
                         UnaryOperation unary_op) -> OutputIt {
   while (first != last) {
      *d_first++ = kblib::invoke(unary_op, *first);
      ++first;
   }
   return d_first;
}
 
template <typename InputIt, typename EndIt, typename InputIt2,
          typename OutputIt, typename BinaryOperation>
constexpr auto transform(InputIt first, EndIt last, InputIt first2,
                         OutputIt d_first, BinaryOperation binary_op)
    -> OutputIt {
   while (first != last) {
      *d_first++ = kblib::invoke(binary_op, *first, *first2);
      ++first;
      ++first2;
   }
   return d_first;
}
 
template <typename InputIt, typename EndIt, typename OutputIt,
          typename UnaryPredicate, typename UnaryOperation>
constexpr auto transform_if(InputIt first, EndIt last, OutputIt d_first,
                            UnaryPredicate pred, UnaryOperation unary_op)
    -> OutputIt {
   while (first != last) {
      if (kblib::invoke(pred, *first)) {
         *d_first++ = kblib::invoke(unary_op, *first);
      }
      ++first;
   }
   return d_first;
}
 
namespace detail_algorithm {
 
   template <class ForwardIt>
   constexpr auto shift_backward(
       ForwardIt first, ForwardIt n_first,
       ForwardIt last) noexcept(noexcept(*first = std::move(*first))) -> void {
      if (first == n_first or n_first == last)
         return;
 
      ForwardIt read = n_first;
      ForwardIt write = first;
 
      while (read != last) {
         *(write++) = std::move(*(read++));
      }
 
      return;
   }
 
} // namespace detail_algorithm
 
} // namespace KBLIB_NS
 
#endif // ALGORITHM_H