Problem p02709 (C++)

Buggy submission (status: Time Limit Exceeded):
#ifndef DEBUG
#define NDEBUG
#endif
#include <algorithm>
#include <array>
#include <cassert>
#include <iostream>
#include <iterator>
#include <limits>
#include <numeric>
#include <string>
#include <type_traits>
#include <utility>
#include <vector>

using namespace std;

// template {{{
// misc {{{
using Z = long long;
[[maybe_unused]] constexpr Z INF = numeric_limits<Z>::max() / 3;
// }}}

// debug {{{
template <class T>
using enable_if_sequence_t = enable_if_t<
    is_same<typename iterator_traits<typename remove_cv_t<
                remove_reference_t<T>>::iterator>::iterator_category,
            random_access_iterator_tag>{}>;
#ifdef NDEBUG
#define dump(x)
#define debug if (0)
template <class T> inline T &&ix(T &&value) { return value; }
template <class T, class Index, class... Indices,
          class = enable_if_sequence_t<T>>
inline auto &&ix(T &&container, Index index, Indices... indices) {
  return ix(container[index], indices...);
}
#else
#define dump(x)                                                                \
  do {                                                                         \
    cerr << "\e[33m[dump: " << __LINE__ << "] " << (#x) << " = " << x          \
         << "\e[0m" << endl;                                                   \
  } while (0);
#define debug
template <class T>
inline auto &&ix_impl([[maybe_unused]] int line,
                      [[maybe_unused]] const char *code, T &&value) {
  return value;
}
template <class T, class Index, class... Indices,
          class = enable_if_sequence_t<T>>
inline auto &&ix_impl(int line, const char *code, T &&container, Index index,
                      Indices... indices) {
  if (index < 0) {
    cerr << "\e[31mix: negative index at line " << line << ", ix(" << code
         << ")\n"
         << "index = " << index << "\e[0m" << endl;
    exit(1);
  }
  int size = distance(begin(container), end(container));
  if (index >= size) {
    cerr << "\e[31mix: index out of range at line " << line << ", ix(" << code
         << ")\n"
         << "index = " << index << " whereas size = " << size << "\e[0m"
         << endl;
    exit(1);
  }
  return ix_impl(line, code, container[index], indices...);
}
#define ix(...) ix_impl(__LINE__, #__VA_ARGS__, __VA_ARGS__)
#endif
// }}}

// IO {{{
template <class T, class U> ostream &operator<<(ostream &os, pair<T, U> p) {
  os << '(' << p.first << ", " << p.second << ')';
  return os;
}
template <class T, class U> istream &operator>>(istream &is, pair<T, U> &p) {
  is >> p.first >> p.second;
  return is;
}
template <class T> false_type is_container_impl(...);
template <class T, class = typename T::iterator> true_type is_container_impl(T);
template <class T>
struct is_container : decltype(is_container_impl<T>(declval<T>())) {};
template <> struct is_container<string> : std::false_type {};
template <class Container, class = enable_if_t<is_container<Container>{}>>
istream &operator>>(istream &is, Container &cont) {
  for (auto &v : cont)
    is >> v;
  return is;
}
template <class Container, class = enable_if_t<is_container<Container>{}>>
ostream &operator<<(ostream &os, Container const &cont) {
  bool first = true;
  constexpr char sep =
      is_container<typename Container::value_type>{} ? '\n' : ' ';
  for (auto const &v : cont) {
    if (!first) {
      os << sep;
    }
    first = false;
    os << v;
  }
  return os;
}
// }}}
// }}}

int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  cout.precision(10);
  cout << fixed;
  Z N;
  cin >> N;
  vector<pair<Z, Z>> As(N);
  for (auto i = 0; i < N; i++) {
    cin >> ix(As, i).first;
    ix(As, i).second = i;
  }
  sort(rbegin(As), rend(As));
  vector<vector<Z>> dp(N + 1, vector<Z>(N + 1));
  auto max_gladness_aux = [&](auto &&self, Z left, Z right) -> Z {
    auto recur = [&](auto... args) { return self(self, args...); };
    dump(left);
    dump(right);
    Z ans = ix(dp, left, right);
    if (ans > 0)
      return ans;
    Z next = N - (right - left);
    if (next == N)
      return 0;
    Z orig = ix(As, next).second;
    ans = recur(left + 1, right) + ix(As, next).first * abs(left - orig);
    ans = max(ans, recur(left, right - 1) +
                       ix(As, next).first * abs(right - 1 - orig));
    return ans;
  };
  cout << max_gladness_aux(max_gladness_aux, 0, N) << '\n';
}


Fixed submission:
#ifndef DEBUG
#define NDEBUG
#endif
#include <algorithm>
#include <array>
#include <cassert>
#include <iostream>
#include <iterator>
#include <limits>
#include <numeric>
#include <string>
#include <type_traits>
#include <utility>
#include <vector>

using namespace std;

// template {{{
// misc {{{
using Z = long long;
[[maybe_unused]] constexpr Z INF = numeric_limits<Z>::max() / 3;
// }}}

// debug {{{
template <class T>
using enable_if_sequence_t = enable_if_t<
    is_same<typename iterator_traits<typename remove_cv_t<
                remove_reference_t<T>>::iterator>::iterator_category,
            random_access_iterator_tag>{}>;
#ifdef NDEBUG
#define dump(x)
#define debug if (0)
template <class T> inline T &&ix(T &&value) { return value; }
template <class T, class Index, class... Indices,
          class = enable_if_sequence_t<T>>
inline auto &&ix(T &&container, Index index, Indices... indices) {
  return ix(container[index], indices...);
}
#else
#define dump(x)                                                                \
  do {                                                                         \
    cerr << "\e[33m[dump: " << __LINE__ << "] " << (#x) << " = " << x          \
         << "\e[0m" << endl;                                                   \
  } while (0);
#define debug
template <class T>
inline auto &&ix_impl([[maybe_unused]] int line,
                      [[maybe_unused]] const char *code, T &&value) {
  return value;
}
template <class T, class Index, class... Indices,
          class = enable_if_sequence_t<T>>
inline auto &&ix_impl(int line, const char *code, T &&container, Index index,
                      Indices... indices) {
  if (index < 0) {
    cerr << "\e[31mix: negative index at line " << line << ", ix(" << code
         << ")\n"
         << "index = " << index << "\e[0m" << endl;
    exit(1);
  }
  int size = distance(begin(container), end(container));
  if (index >= size) {
    cerr << "\e[31mix: index out of range at line " << line << ", ix(" << code
         << ")\n"
         << "index = " << index << " whereas size = " << size << "\e[0m"
         << endl;
    exit(1);
  }
  return ix_impl(line, code, container[index], indices...);
}
#define ix(...) ix_impl(__LINE__, #__VA_ARGS__, __VA_ARGS__)
#endif
// }}}

// IO {{{
template <class T, class U> ostream &operator<<(ostream &os, pair<T, U> p) {
  os << '(' << p.first << ", " << p.second << ')';
  return os;
}
template <class T, class U> istream &operator>>(istream &is, pair<T, U> &p) {
  is >> p.first >> p.second;
  return is;
}
template <class T> false_type is_container_impl(...);
template <class T, class = typename T::iterator> true_type is_container_impl(T);
template <class T>
struct is_container : decltype(is_container_impl<T>(declval<T>())) {};
template <> struct is_container<string> : std::false_type {};
template <class Container, class = enable_if_t<is_container<Container>{}>>
istream &operator>>(istream &is, Container &cont) {
  for (auto &v : cont)
    is >> v;
  return is;
}
template <class Container, class = enable_if_t<is_container<Container>{}>>
ostream &operator<<(ostream &os, Container const &cont) {
  bool first = true;
  constexpr char sep =
      is_container<typename Container::value_type>{} ? '\n' : ' ';
  for (auto const &v : cont) {
    if (!first) {
      os << sep;
    }
    first = false;
    os << v;
  }
  return os;
}
// }}}
// }}}

int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  cout.precision(10);
  cout << fixed;
  Z N;
  cin >> N;
  vector<pair<Z, Z>> As(N);
  for (auto i = 0; i < N; i++) {
    cin >> ix(As, i).first;
    ix(As, i).second = i;
  }
  sort(rbegin(As), rend(As));
  vector<vector<Z>> dp(N + 1, vector<Z>(N + 1));
  auto max_gladness_aux = [&](auto &&self, Z left, Z right) -> Z {
    auto recur = [&](auto... args) { return self(self, args...); };
    dump(left);
    dump(right);
    Z &ans = ix(dp, left, right);
    if (ans > 0)
      return ans;
    Z next = N - (right - left);
    if (next == N)
      return 0;
    Z orig = ix(As, next).second;
    ans = recur(left + 1, right) + ix(As, next).first * abs(left - orig);
    ans = max(ans, recur(left, right - 1) +
                       ix(As, next).first * abs(right - 1 - orig));
    return ans;
  };
  cout << max_gladness_aux(max_gladness_aux, 0, N) << '\n';
}