Problem p03602 (C++)

Buggy submission (status: Time Limit Exceeded):
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using VI = vector<int>;
using VL = vector<ll>;
template <class T> using PQ = priority_queue<T, vector<T>, greater<T>>;
#define FOR(i, a, n) for (int(i) = (a); (i) < (n); ++(i))
#define eFOR(i, a, n) for (int(i) = (a); (i) <= (n); ++(i))
#define rFOR(i, a, n) for (int(i) = (n)-1; (i) >= (a); --(i))
#define erFOR(i, a, n) for (int(i) = (n); (i) >= (a); --(i))
#define each(i, a) for (auto &i : a)
#define SORT(i) sort((i).begin(), (i).end())
#define rSORT(i, a) sort((i).begin(), (i).end(), (a))
#define all(i) (i).begin(), (i).end()
#define out(y, x) ((y) < 0 || h <= (y) || (x) < 0 || w <= (x))
#define line cout << "------------------------\n"
#define ENDL(i, n) ((i) == (n)-1 ? "\n" : " ")
#define stop system("pause")
constexpr ll INF = 1000000000;
constexpr ll LLINF = 1LL << 60;
constexpr ll mod = 1000000007;
constexpr ll MOD = 998244353;
const long double pi = acos(-1);
const long double eps = 1e-10;
template <class T> inline bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T> inline bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return 1;
  }
  return 0;
}
inline void init() {
  cin.tie(nullptr);
  cout.tie(nullptr);
  ios::sync_with_stdio(false);
  cout << fixed << setprecision(15);
}
template <class T> inline istream &operator>>(istream &is, vector<T> &v) {
  for (auto &elemnt : v)
    is >> elemnt;
  return is;
}
template <class T, class U>
inline istream &operator>>(istream &is, pair<T, U> &p) {
  is >> p.first >> p.second;
  return is;
}
template <class T> inline vector<T> vec(size_t a) { return vector<T>(a); }
template <class T> inline vector<T> defvec(T def, size_t a) {
  return vector<T>(a, def);
}
template <class T, class... Ts> inline auto vec(size_t a, Ts... ts) {
  return vector<decltype(vec<T>(ts...))>(a, vec<T>(ts...));
}
template <class T, class... Ts> inline auto defvec(T def, size_t a, Ts... ts) {
  return vector<decltype(defvec<T>(def, ts...))>(a, defvec<T>(def, ts...));
}

using dat = tuple<ll, int, int>;
int main() {
  init();

  int n;
  cin >> n;
  vector<dat> a;
  FOR(i, 0, n) FOR(j, 0, n) {
    ll in;
    cin >> in;
    if (j <= i)
      continue;
    a.emplace_back(in, i, j);
  }

  SORT(a);
  auto dis = defvec<ll>(LLINF, n, n);
  FOR(i, 0, n) dis[i][i] = 0;

  ll ans = 0;
  each(i, a) {
    ll cost;
    int x, y;
    tie(cost, x, y) = i;
    if (dis[x][y] < cost) {
      ans = -1;
      break;
    }
    if (chmin(dis[x][y], cost) && chmin(dis[y][x], cost)) {
      ans += cost;
    }
    FOR(j, 0, n) FOR(k, 0, n) {
      chmin(dis[j][k], dis[j][x] + dis[x][k]);
      chmin(dis[j][k], dis[j][y] + dis[y][k]);
    }
  }

  cout << ans << "\n";
}


Fixed submission:
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using VI = vector<int>;
using VL = vector<ll>;
template <class T> using PQ = priority_queue<T, vector<T>, greater<T>>;
#define FOR(i, a, n) for (int(i) = (a); (i) < (n); ++(i))
#define eFOR(i, a, n) for (int(i) = (a); (i) <= (n); ++(i))
#define rFOR(i, a, n) for (int(i) = (n)-1; (i) >= (a); --(i))
#define erFOR(i, a, n) for (int(i) = (n); (i) >= (a); --(i))
#define each(i, a) for (auto &i : a)
#define SORT(i) sort((i).begin(), (i).end())
#define rSORT(i, a) sort((i).begin(), (i).end(), (a))
#define all(i) (i).begin(), (i).end()
#define out(y, x) ((y) < 0 || h <= (y) || (x) < 0 || w <= (x))
#define line cout << "------------------------\n"
#define ENDL(i, n) ((i) == (n)-1 ? "\n" : " ")
#define stop system("pause")
constexpr ll INF = 1000000000;
constexpr ll LLINF = 1LL << 60;
constexpr ll mod = 1000000007;
constexpr ll MOD = 998244353;
const long double pi = acos(-1);
const long double eps = 1e-10;
template <class T> inline bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T> inline bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return 1;
  }
  return 0;
}
inline void init() {
  cin.tie(nullptr);
  cout.tie(nullptr);
  ios::sync_with_stdio(false);
  cout << fixed << setprecision(15);
}
template <class T> inline istream &operator>>(istream &is, vector<T> &v) {
  for (auto &elemnt : v)
    is >> elemnt;
  return is;
}
template <class T, class U>
inline istream &operator>>(istream &is, pair<T, U> &p) {
  is >> p.first >> p.second;
  return is;
}
template <class T> inline vector<T> vec(size_t a) { return vector<T>(a); }
template <class T> inline vector<T> defvec(T def, size_t a) {
  return vector<T>(a, def);
}
template <class T, class... Ts> inline auto vec(size_t a, Ts... ts) {
  return vector<decltype(vec<T>(ts...))>(a, vec<T>(ts...));
}
template <class T, class... Ts> inline auto defvec(T def, size_t a, Ts... ts) {
  return vector<decltype(defvec<T>(def, ts...))>(a, defvec<T>(def, ts...));
}

using dat = tuple<ll, int, int>;
int main() {
  init();

  int n;
  cin >> n;
  vector<dat> a;
  FOR(i, 0, n) FOR(j, 0, n) {
    ll in;
    cin >> in;
    if (j <= i)
      continue;
    a.emplace_back(in, i, j);
  }

  SORT(a);
  auto dis = defvec<ll>(LLINF, n, n);
  FOR(i, 0, n) dis[i][i] = 0;

  ll ans = 0;
  each(i, a) {
    ll cost;
    int x, y;
    tie(cost, x, y) = i;
    if (dis[x][y] < cost) {
      ans = -1;
      break;
    }
    if (chmin(dis[x][y], cost) && chmin(dis[y][x], cost)) {
      ans += cost;
    }
    FOR(j, 0, n) {
      chmin(dis[x][j], dis[x][y] + dis[y][j]);
      chmin(dis[j][x], dis[j][y] + dis[y][x]);
      chmin(dis[y][j], dis[y][x] + dis[x][j]);
      chmin(dis[j][y], dis[j][x] + dis[x][y]);
    }
  }

  cout << ans << "\n";
}