Problem p02978 (C++)

Buggy submission (status: Runtime Error):
#include <bits/stdc++.h>
#pragma GCC diagnostic ignored "-Wsign-compare"
#pragma GCC diagnostic ignored "-Wsign-conversion"
#define NDEBUG
#define SHOW(...) static_cast<void>(0)
//!===========================================================!//
//!  dP     dP                          dP                    !//
//!  88     88                          88                    !//
//!  88aaaaa88a .d8888b. .d8888b. .d888b88 .d8888b. 88d888b.  !//
//!  88     88  88ooood8 88'  '88 88'  '88 88ooood8 88'  '88  !//
//!  88     88  88.  ... 88.  .88 88.  .88 88.  ... 88        !//
//!  dP     dP  '88888P' '88888P8 '88888P8 '88888P' dP        !//
//!===========================================================!//
template <typename T> T read() {
  T v;
  return std::cin >> v, v;
}
template <typename T> std::vector<T> readVec(const std::size_t l) {
  std::vector<T> v(l);
  for (auto &e : v) {
    std::cin >> e;
  }
  return v;
}
using ld = long double;
using uint = unsigned int;
using ll = long long;
using ull = unsigned long long;
constexpr unsigned int MOD = 1000000007;
template <typename T> constexpr T INF = std::numeric_limits<T>::max() / 4;
template <typename F> constexpr F PI = static_cast<F>(3.1415926535897932385);
std::mt19937 mt{std::random_device{}()};
template <typename T> bool chmin(T &a, const T &b) {
  return (a > b ? a = b, true : false);
}
template <typename T> bool chmax(T &a, const T &b) {
  return (a < b ? a = b, true : false);
}
template <typename T> std::vector<T> Vec(const std::size_t n, T v) {
  return std::vector<T>(n, v);
}
template <class... Args> auto Vec(const std::size_t n, Args... args) {
  return std::vector<decltype(Vec(args...))>(n, Vec(args...));
}
template <typename T> constexpr T popCount(const T u) {
#ifdef __has_builtin
  return u == 0 ? T(0) : (T)__builtin_popcountll(u);
#else
  unsigned long long v = static_cast<unsigned long long>(u);
  return v = (v & 0x5555555555555555ULL) + (v >> 1 & 0x5555555555555555ULL),
         v = (v & 0x3333333333333333ULL) + (v >> 2 & 0x3333333333333333ULL),
         v = (v + (v >> 4)) & 0x0F0F0F0F0F0F0F0FULL,
         static_cast<T>(v * 0x0101010101010101ULL >> 56 & 0x7f);
#endif
}
template <typename T> constexpr T log2p1(const T u) {
#ifdef __has_builtin
  return u == 0 ? T(0) : T(64 - __builtin_clzll(u));
#else
  unsigned long long v = static_cast<unsigned long long>(u);
  return v = static_cast<unsigned long long>(v), v |= (v >> 1), v |= (v >> 2),
         v |= (v >> 4), v |= (v >> 8), v |= (v >> 16), v |= (v >> 32),
         popCount(v);
#endif
}
template <typename T> constexpr T clog(const T v) {
  return v == 0 ? T(0) : log2p1(v - 1);
}
template <typename T> constexpr T msbp1(const T v) { return log2p1(v); }
template <typename T> constexpr T lsbp1(const T v) {
#ifdef __has_builtin
  return __builtin_ffsll(v);
#else
  return v == 0 ? T(0) : popCount((v & (-v)) - T(1)) + T(1);
#endif
}
template <typename T> constexpr bool ispow2(const T v) {
  return popCount(v) == 1;
}
template <typename T> constexpr T ceil2(const T v) {
  return v == 0 ? T(1) : T(1) << log2p1(v - 1);
}
template <typename T> constexpr T floor2(const T v) {
  return v == 0 ? T(0) : T(1) << (log2p1(v) - 1);
}
//!=====================================!//
//!  8888ba.88ba           oo           !//
//!  88  '8b  '8b                       !//
//!  88   88   88 .d8888b. dP 88d888b.  !//
//!  88   88   88 88'  '88 88 88'  '88  !//
//!  88   88   88 88.  .88 88 88    88  !//
//!  dP   dP   dP '88888P8 dP dP    dP  !//
//!=====================================!//
using MP = std::map<ll, ll>;
using P = std::pair<ll, ll>;
MP memo[17][17];
bool calced[17][17];
int main() {
  const int N = read<int>();
  const auto A = readVec<ll>(N);
  if (N == 2) {
    return std::cout << A[0] + A[1] << std::endl, 0;
  }
  auto dfs = [&, N](auto &&self, const int l, const int r) -> MP {
    if (r - l == 0) {
      return MP{{0, 0}};
    }
    if (calced[l][r]) {
      return memo[l][r];
    }
    MP l2r, r2l;
    for (int i = l; i < r; i++) {
      const auto lmp = self(self, l, i);
      const auto rmp = self(self, i + 1, r);
      for (const auto &lp : lmp) {
        const ll al = lp.first, ar = lp.second;
        for (const auto &rp : rmp) {
          const ll bl = rp.first, br = rp.second;
          const ll L = A[i] + ar + bl + al;
          const ll R = A[i] + ar + bl + br;
          if (l2r.find(L) != l2r.end()) {
            const ll oldR = l2r[L];
            if (oldR <= R) {
              continue;
            }
          }
          if (r2l.find(R) != r2l.end()) {
            const ll oldL = r2l[R];
            if (oldL <= L) {
              continue;
            }
          }
          l2r[L] = R, r2l[R] = L;
        }
      }
    }
    ll prevR = INF<ll>;
    MP ans;
    for (const auto &p : l2r) {
      if (prevR > p.second) {
        ans.insert(p), prevR = p.second;
      }
    }
    return calced[l][r] = true, memo[l][r] = ans;
  };
  const auto mp = dfs(dfs, 1, N - 1);
  ll min = INF<ll>;
  for (const auto &p : mp) {
    chmin(min, p.first + p.second);
  }
  std::cout << min + A[0] + A[N - 1] << std::endl;
  return 0;
}


Fixed submission:
#include <bits/stdc++.h>
#pragma GCC diagnostic ignored "-Wsign-compare"
#pragma GCC diagnostic ignored "-Wsign-conversion"
#define NDEBUG
#define SHOW(...) static_cast<void>(0)
//!===========================================================!//
//!  dP     dP                          dP                    !//
//!  88     88                          88                    !//
//!  88aaaaa88a .d8888b. .d8888b. .d888b88 .d8888b. 88d888b.  !//
//!  88     88  88ooood8 88'  '88 88'  '88 88ooood8 88'  '88  !//
//!  88     88  88.  ... 88.  .88 88.  .88 88.  ... 88        !//
//!  dP     dP  '88888P' '88888P8 '88888P8 '88888P' dP        !//
//!===========================================================!//
template <typename T> T read() {
  T v;
  return std::cin >> v, v;
}
template <typename T> std::vector<T> readVec(const std::size_t l) {
  std::vector<T> v(l);
  for (auto &e : v) {
    std::cin >> e;
  }
  return v;
}
using ld = long double;
using uint = unsigned int;
using ll = long long;
using ull = unsigned long long;
constexpr unsigned int MOD = 1000000007;
template <typename T> constexpr T INF = std::numeric_limits<T>::max() / 4;
template <typename F> constexpr F PI = static_cast<F>(3.1415926535897932385);
std::mt19937 mt{std::random_device{}()};
template <typename T> bool chmin(T &a, const T &b) {
  return (a > b ? a = b, true : false);
}
template <typename T> bool chmax(T &a, const T &b) {
  return (a < b ? a = b, true : false);
}
template <typename T> std::vector<T> Vec(const std::size_t n, T v) {
  return std::vector<T>(n, v);
}
template <class... Args> auto Vec(const std::size_t n, Args... args) {
  return std::vector<decltype(Vec(args...))>(n, Vec(args...));
}
template <typename T> constexpr T popCount(const T u) {
#ifdef __has_builtin
  return u == 0 ? T(0) : (T)__builtin_popcountll(u);
#else
  unsigned long long v = static_cast<unsigned long long>(u);
  return v = (v & 0x5555555555555555ULL) + (v >> 1 & 0x5555555555555555ULL),
         v = (v & 0x3333333333333333ULL) + (v >> 2 & 0x3333333333333333ULL),
         v = (v + (v >> 4)) & 0x0F0F0F0F0F0F0F0FULL,
         static_cast<T>(v * 0x0101010101010101ULL >> 56 & 0x7f);
#endif
}
template <typename T> constexpr T log2p1(const T u) {
#ifdef __has_builtin
  return u == 0 ? T(0) : T(64 - __builtin_clzll(u));
#else
  unsigned long long v = static_cast<unsigned long long>(u);
  return v = static_cast<unsigned long long>(v), v |= (v >> 1), v |= (v >> 2),
         v |= (v >> 4), v |= (v >> 8), v |= (v >> 16), v |= (v >> 32),
         popCount(v);
#endif
}
template <typename T> constexpr T clog(const T v) {
  return v == 0 ? T(0) : log2p1(v - 1);
}
template <typename T> constexpr T msbp1(const T v) { return log2p1(v); }
template <typename T> constexpr T lsbp1(const T v) {
#ifdef __has_builtin
  return __builtin_ffsll(v);
#else
  return v == 0 ? T(0) : popCount((v & (-v)) - T(1)) + T(1);
#endif
}
template <typename T> constexpr bool ispow2(const T v) {
  return popCount(v) == 1;
}
template <typename T> constexpr T ceil2(const T v) {
  return v == 0 ? T(1) : T(1) << log2p1(v - 1);
}
template <typename T> constexpr T floor2(const T v) {
  return v == 0 ? T(0) : T(1) << (log2p1(v) - 1);
}
//!=====================================!//
//!  8888ba.88ba           oo           !//
//!  88  '8b  '8b                       !//
//!  88   88   88 .d8888b. dP 88d888b.  !//
//!  88   88   88 88'  '88 88 88'  '88  !//
//!  88   88   88 88.  .88 88 88    88  !//
//!  dP   dP   dP '88888P8 dP dP    dP  !//
//!=====================================!//
using MP = std::map<ll, ll>;
using P = std::pair<ll, ll>;
MP memo[19][19];
bool calced[19][19];
int main() {
  const int N = read<int>();
  const auto A = readVec<ll>(N);
  if (N == 2) {
    return std::cout << A[0] + A[1] << std::endl, 0;
  }
  auto dfs = [&, N](auto &&self, const int l, const int r) -> MP {
    if (r - l == 0) {
      return MP{{0, 0}};
    }
    if (calced[l][r]) {
      return memo[l][r];
    }
    MP l2r, r2l;
    for (int i = l; i < r; i++) {
      const auto lmp = self(self, l, i);
      const auto rmp = self(self, i + 1, r);
      for (const auto &lp : lmp) {
        const ll al = lp.first, ar = lp.second;
        for (const auto &rp : rmp) {
          const ll bl = rp.first, br = rp.second;
          const ll L = A[i] + ar + bl + al;
          const ll R = A[i] + ar + bl + br;
          if (l2r.find(L) != l2r.end()) {
            const ll oldR = l2r[L];
            if (oldR <= R) {
              continue;
            }
          }
          if (r2l.find(R) != r2l.end()) {
            const ll oldL = r2l[R];
            if (oldL <= L) {
              continue;
            }
          }
          l2r[L] = R, r2l[R] = L;
        }
      }
    }
    ll prevR = INF<ll>;
    MP ans;
    for (const auto &p : l2r) {
      if (prevR > p.second) {
        ans.insert(p), prevR = p.second;
      }
    }
    return calced[l][r] = true, memo[l][r] = ans;
  };
  const auto mp = dfs(dfs, 1, N - 1);
  ll min = INF<ll>;
  for (const auto &p : mp) {
    chmin(min, p.first + p.second);
  }
  std::cout << min + A[0] + A[N - 1] << std::endl;
  return 0;
}