Problem p02941 (C++)

Buggy submission (status: Time Limit Exceeded):
#include <bits/stdc++.h>
using namespace std;
#pragma region Macros
#define ios                                                                    \
  ios::sync_with_stdio(false);                                                 \
  cin.tie(nullptr);
#define VEC(type, name, size)                                                  \
  V<type> name(size);                                                          \
  IN(name)
#define VVEC(type, name, h, w)                                                 \
  VV<type> name(h, V<type>(w));                                                \
  IN(name)
#define INT(...)                                                               \
  int __VA_ARGS__;                                                             \
  IN(__VA_ARGS__)
#define LL(...)                                                                \
  ll __VA_ARGS__;                                                              \
  IN(__VA_ARGS__)
#define STR(...)                                                               \
  string __VA_ARGS__;                                                          \
  IN(__VA_ARGS__)
#define CHAR(...)                                                              \
  char __VA_ARGS__;                                                            \
  IN(__VA_ARGS__)
#define DOUBLE(...)                                                            \
  DOUBLE __VA_ARGS__;                                                          \
  IN(__VA_ARGS__)
#define LD(...)                                                                \
  LD __VA_ARGS__;                                                              \
  IN(__VA_ARGS__)
template <class T> void scan(T &a) { cin >> a; }
template <class T> void scan(vector<T> &a) {
  for (auto &i : a)
    scan(i);
}
template <class T, class L> void scan(pair<T, L> &p) {
  scan(p.first);
  scan(p.second);
}
void IN() {}
template <class Head, class... Tail> void IN(Head &head, Tail &...tail) {
  scan(head);
  IN(tail...);
}
template <class T> inline void print(T x) { cout << x << '\n'; }
#define ll long long
#define ld long double
#define FOR(i, l, r) for (ll i = (l); i < (r); ++i)
#define REP(i, n) FOR(i, 0, n)
#define REPS(i, n) FOR(i, 1, n + 1)
#define RFOR(i, l, r) for (ll i = (l); i >= (r); --i)
#define RREP(i, n) RFOR(i, n - 1, 0)
#define RREPS(i, n) RFOR(i, n, 1)
#define pb push_back
#define eb emplace_back
#define SZ(x) ((ll)(x).size())
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
template <class T = ll> using V = vector<T>;
template <class T = ll> using VV = V<V<T>>;
template <class T> inline bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> inline bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
inline void Yes(bool b = true) { cout << (b ? "Yes" : "No") << '\n'; }
inline void YES(bool b = true) { cout << (b ? "YES" : "NO") << '\n'; }
inline void err(bool b = true) {
  if (b) {
    cout << -1 << '\n';
    exit(0);
  }
}
template <class T> inline void fin(bool b = true, T e = 0) {
  if (b) {
    cout << e << '\n';
    exit(0);
  }
}
template <class T> T Roundup_div(T x, T y) { return (x + (y - 1)) / y; }
template <typename T> T pow(T a, long long n, T e = 1) {
  T ret = e;
  while (n) {
    if (n & 1)
      ret *= a;
    a *= a;
    n >>= 1;
  }
  return ret;
}
const ll INF = 1e18;
#pragma endregion

using P = pair<int, int>;

int main() {
  ios;
  INT(n);
  VEC(int, a, n);
  VEC(int, b, n);
  priority_queue<P> q;
  REP(i, n) {
    if (b[i] > a[i])
      q.push({b[i], i});
    if (b[i] < a[i]) {
      print(-1);
      return 0;
    }
  }
  ll cnt = 0;
  while (SZ(q)) {
    P p = q.top();
    q.pop();
    ll s = p.second;
    ll sum = b[(s ? s - 1 : n - 1)] + b[(s == n - 1 ? 0 : s + 1)];
    cnt += (b[s] - a[s]) / sum;
    b[s] -= (b[s] - a[s]) / sum * sum;
    if (a[s] != b[s])
      q.push({b[s], s});
  }
  print(cnt);
}

Fixed submission:
#include <bits/stdc++.h>
using namespace std;
#pragma region Macros
#define ios                                                                    \
  ios::sync_with_stdio(false);                                                 \
  cin.tie(nullptr);
#define VEC(type, name, size)                                                  \
  V<type> name(size);                                                          \
  IN(name)
#define VVEC(type, name, h, w)                                                 \
  VV<type> name(h, V<type>(w));                                                \
  IN(name)
#define INT(...)                                                               \
  int __VA_ARGS__;                                                             \
  IN(__VA_ARGS__)
#define LL(...)                                                                \
  ll __VA_ARGS__;                                                              \
  IN(__VA_ARGS__)
#define STR(...)                                                               \
  string __VA_ARGS__;                                                          \
  IN(__VA_ARGS__)
#define CHAR(...)                                                              \
  char __VA_ARGS__;                                                            \
  IN(__VA_ARGS__)
#define DOUBLE(...)                                                            \
  DOUBLE __VA_ARGS__;                                                          \
  IN(__VA_ARGS__)
#define LD(...)                                                                \
  LD __VA_ARGS__;                                                              \
  IN(__VA_ARGS__)
template <class T> void scan(T &a) { cin >> a; }
template <class T> void scan(vector<T> &a) {
  for (auto &i : a)
    scan(i);
}
template <class T, class L> void scan(pair<T, L> &p) {
  scan(p.first);
  scan(p.second);
}
void IN() {}
template <class Head, class... Tail> void IN(Head &head, Tail &...tail) {
  scan(head);
  IN(tail...);
}
template <class T> inline void print(T x) { cout << x << '\n'; }
#define ll long long
#define ld long double
#define FOR(i, l, r) for (ll i = (l); i < (r); ++i)
#define REP(i, n) FOR(i, 0, n)
#define REPS(i, n) FOR(i, 1, n + 1)
#define RFOR(i, l, r) for (ll i = (l); i >= (r); --i)
#define RREP(i, n) RFOR(i, n - 1, 0)
#define RREPS(i, n) RFOR(i, n, 1)
#define pb push_back
#define eb emplace_back
#define SZ(x) ((ll)(x).size())
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
template <class T = ll> using V = vector<T>;
template <class T = ll> using VV = V<V<T>>;
template <class T> inline bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> inline bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
inline void Yes(bool b = true) { cout << (b ? "Yes" : "No") << '\n'; }
inline void YES(bool b = true) { cout << (b ? "YES" : "NO") << '\n'; }
inline void err(bool b = true) {
  if (b) {
    cout << -1 << '\n';
    exit(0);
  }
}
template <class T> inline void fin(bool b = true, T e = 0) {
  if (b) {
    cout << e << '\n';
    exit(0);
  }
}
template <class T> T Roundup_div(T x, T y) { return (x + (y - 1)) / y; }
template <typename T> T pow(T a, long long n, T e = 1) {
  T ret = e;
  while (n) {
    if (n & 1)
      ret *= a;
    a *= a;
    n >>= 1;
  }
  return ret;
}
const ll INF = 1e18;
#pragma endregion

using P = pair<int, int>;

int main() {
  ios;
  INT(n);
  VEC(int, a, n);
  VEC(int, b, n);
  priority_queue<P> q;
  REP(i, n) {
    if (b[i] > a[i])
      q.push({b[i], i});
    if (b[i] < a[i]) {
      print(-1);
      return 0;
    }
  }
  ll cnt = 0;
  while (SZ(q)) {
    P p = q.top();
    q.pop();
    ll s = p.second;
    ll sum = b[(s ? s - 1 : n - 1)] + b[(s == n - 1 ? 0 : s + 1)];
    ll t = (b[s] - a[s]) / sum;
    if (!t) {
      print(-1);
      return 0;
    }
    cnt += t;
    b[s] -= t * sum;
    if (a[s] != b[s])
      q.push({b[s], s});
  }
  print(cnt);
}