Problem p02925 (C++)

Buggy submission (status: Time Limit Exceeded):
#define DEBUG 1
#include <algorithm>
#include <cmath>
#include <cstring>
#include <deque>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <string>
#include <tuple>
#include <utility>
#include <vector>
using namespace std;
using ll = long long;
using ull = unsigned long long;
using vll = vector<ll>;
using vvll = vector<vll>;
using pll = pair<ll, ll>;
using tll = tuple<ll, ll, ll>;
#define all(v) (v).begin(), (v).end()
#define for1(i, n) for (ll i = 0; i < (n); i++)
#define for2(i, m, n) for (ll i = (m); i < (n); i++)
#define for3(i, m, n, d) for (ll i = (m); i < (n); i += (d))
#define rfor2(i, m, n) for (ll i = (m); i > (n); i--)
#define rfor3(i, m, n, d) for (ll i = (m); i > (n); i += (d))
#define INF 1111111111111111111LL
#define MOD 1000000007LL // 10**9 + 7
#define print(...) print_1(__VA_ARGS__)
#if DEBUG
#define dump(...) dump_1(#__VA_ARGS__, __VA_ARGS__)
#else
#define dump(...)
#endif
template <typename Head> void dump_1(const char *str, Head &&h) {
  cerr << str << ": " << h << '\n';
}
template <typename Head, typename... Tail>
void dump_1(const char *str, Head &&h, Tail &&...t) {
  while (*str != ',') {
    cerr << *str++;
  }
  cerr << ": " << h << ' ';
  dump_1(str + 1, t...);
}
template <typename T1, typename T2>
ostream &operator<<(ostream &os, const pair<T1, T2> &v) {
  os << '(' << v.first << ", " << v.second << ')';
  return os;
}
template <typename T1, typename T2, typename T3>
ostream &operator<<(ostream &os, const tuple<T1, T2, T3> &v) {
  os << '(' << get<0>(v) << ", " << get<1>(v) << ", " << get<2>(v) << ')';
  return os;
}
template <typename T> ostream &operator<<(ostream &os, const vector<T> &v) {
  for (auto it = v.begin(); it != v.end(); it++) {
    if (it != v.begin()) {
      os << ' ';
    }
    os << *it;
  }
  return os;
}
template <typename T> ostream &operator<<(ostream &os, const set<T> &v) {
  for (auto it = v.begin(); it != v.end(); it++) {
    if (it != v.begin()) {
      os << ' ';
    }
    os << *it;
  }
  return os;
}
template <typename T1, typename T2>
ostream &operator<<(ostream &os, const map<T1, T2> &v) {
  os << '{';
  for (auto it = v.begin(); it != v.end(); it++) {
    if (it != v.begin()) {
      os << ", ";
    }
    os << it->first << ':' << it->second;
  }
  os << '}';
  return os;
}
void Yes(void) { cout << "Yes" << '\n'; }
void No(void) { cout << "No" << '\n'; }
void YES(void) { cout << "YES" << '\n'; }
void NO(void) { cout << "NO" << '\n'; }
template <typename T> void chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
  }
}
template <typename T> void chmin(T &a, const T &b) {
  if (a > b) {
    a = b;
  }
}
template <typename T> void vin(vector<T> &v, ll len) {
  for1(i, len) { cin >> v[i]; }
}
template <typename Head> void print_1(Head &&h) { cout << h << '\n'; }
template <typename Head, typename... Tail> void print_1(Head &&h, Tail &&...t) {
  cout << h << ' ';
  print_1(t...);
}
//---------------------------------------------------------
ll A[1001][1001];
ll c[2][1001];
void solve() {
  ll ans = 0;
  ll N;
  cin >> N;
  for1(h, N) {
    for1(w, N - 1) {
      ll a;
      cin >> a;
      A[h][w] = a - 1;
    }
  }
  bool loop = true;
  ll t0 = 1;
  ll t1 = 0;
  while (loop) {
    loop = false;
    t0 = 1 - t0;
    t1 = 1 - t1;
    for1(i, N) {
      if (c[t0][i] == N - 1)
        continue;
      for2(j, i + 1, N) {
        if (c[t0][j] == N - 1)
          continue;
        if (A[i][c[t0][i]] == j && A[j][c[t0][j]] == i) {
          c[t1][i] = c[t0][i] + 1;
          c[t1][j] = c[t0][j] + 1;
          loop = true;
        }
      }
    }
    for1(i, N) { chmax(c[t1][i], c[t0][i]); }
    if (loop) {
      ans++;
    }
  }
  for1(i, N) {
    if (c[t1][i] < N - 1) {
      print(-1);
      return;
    }
  }

  print(ans);
}

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout << fixed << setprecision(12);
  cerr << fixed << setprecision(12);
  solve();
}


Fixed submission:
#define DEBUG 1
#include <algorithm>
#include <cmath>
#include <cstring>
#include <deque>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <string>
#include <tuple>
#include <utility>
#include <vector>
using namespace std;
using ll = long long;
using ull = unsigned long long;
using vll = vector<ll>;
using vvll = vector<vll>;
using pll = pair<ll, ll>;
using tll = tuple<ll, ll, ll>;
#define all(v) (v).begin(), (v).end()
#define for1(i, n) for (ll i = 0; i < (n); i++)
#define for2(i, m, n) for (ll i = (m); i < (n); i++)
#define for3(i, m, n, d) for (ll i = (m); i < (n); i += (d))
#define rfor2(i, m, n) for (ll i = (m); i > (n); i--)
#define rfor3(i, m, n, d) for (ll i = (m); i > (n); i += (d))
#define INF 1111111111111111111LL
#define MOD 1000000007LL // 10**9 + 7
#define print(...) print_1(__VA_ARGS__)
#if DEBUG
#define dump(...) dump_1(#__VA_ARGS__, __VA_ARGS__)
#else
#define dump(...)
#endif
template <typename Head> void dump_1(const char *str, Head &&h) {
  cerr << str << ": " << h << '\n';
}
template <typename Head, typename... Tail>
void dump_1(const char *str, Head &&h, Tail &&...t) {
  while (*str != ',') {
    cerr << *str++;
  }
  cerr << ": " << h << ' ';
  dump_1(str + 1, t...);
}
template <typename T1, typename T2>
ostream &operator<<(ostream &os, const pair<T1, T2> &v) {
  os << '(' << v.first << ", " << v.second << ')';
  return os;
}
template <typename T1, typename T2, typename T3>
ostream &operator<<(ostream &os, const tuple<T1, T2, T3> &v) {
  os << '(' << get<0>(v) << ", " << get<1>(v) << ", " << get<2>(v) << ')';
  return os;
}
template <typename T> ostream &operator<<(ostream &os, const vector<T> &v) {
  for (auto it = v.begin(); it != v.end(); it++) {
    if (it != v.begin()) {
      os << ' ';
    }
    os << *it;
  }
  return os;
}
template <typename T> ostream &operator<<(ostream &os, const set<T> &v) {
  for (auto it = v.begin(); it != v.end(); it++) {
    if (it != v.begin()) {
      os << ' ';
    }
    os << *it;
  }
  return os;
}
template <typename T1, typename T2>
ostream &operator<<(ostream &os, const map<T1, T2> &v) {
  os << '{';
  for (auto it = v.begin(); it != v.end(); it++) {
    if (it != v.begin()) {
      os << ", ";
    }
    os << it->first << ':' << it->second;
  }
  os << '}';
  return os;
}
void Yes(void) { cout << "Yes" << '\n'; }
void No(void) { cout << "No" << '\n'; }
void YES(void) { cout << "YES" << '\n'; }
void NO(void) { cout << "NO" << '\n'; }
template <typename T> void chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
  }
}
template <typename T> void chmin(T &a, const T &b) {
  if (a > b) {
    a = b;
  }
}
template <typename T> void vin(vector<T> &v, ll len) {
  for1(i, len) { cin >> v[i]; }
}
template <typename Head> void print_1(Head &&h) { cout << h << '\n'; }
template <typename Head, typename... Tail> void print_1(Head &&h, Tail &&...t) {
  cout << h << ' ';
  print_1(t...);
}
//---------------------------------------------------------
ll A[1001][1001];
ll c[2][1001];
void solve() {
  ll ans = 0;
  ll N;
  cin >> N;
  for1(h, N) {
    for1(w, N - 1) {
      ll a;
      cin >> a;
      A[h][w] = a - 1;
    }
  }
  bool loop = true;
  ll t0 = 1;
  ll t1 = 0;
  while (loop) {
    loop = false;
    t0 = 1 - t0;
    t1 = 1 - t1;
    for1(i, N) {
      if (c[t0][i] == N - 1)
        continue;
      ll j = A[i][c[t0][i]];
      if (c[t0][j] == N - 1)
        continue;
      if (A[j][c[t0][j]] == i) {
        c[t1][i] = c[t0][i] + 1;
        c[t1][j] = c[t0][j] + 1;
        loop = true;
      }
    }
    for1(i, N) { chmax(c[t1][i], c[t0][i]); }
    if (loop) {
      ans++;
    }
  }
  for1(i, N) {
    if (c[t1][i] < N - 1) {
      print(-1);
      return;
    }
  }

  print(ans);
}

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout << fixed << setprecision(12);
  cerr << fixed << setprecision(12);
  solve();
}