Problem p01136 (C++) — buggy submission, verdict: Runtime Error

#include <algorithm>
#include <bitset>
#include <cassert>
#include <climits>
#include <cmath>
#include <complex>
#include <cstddef>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <fstream>
#include <iomanip>
#include <iostream>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <tuple>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

using namespace std;
#define REP(i, n) for (int(i) = 0; (i) < (n); (i)++)
#define FOR(i, a, b) for (int(i) = (a); (i) < (b); (i)++)
#define RREP(i, a) for (int(i) = (a)-1; (i) >= 0; (i)--)
#define FORR(i, a, b) for (int(i) = (a)-1; (i) >= (b); (i)--)
#define DEBUG(C) cerr << #C << " = " << C << endl;
using LL = long long;
using VI = vector<int>;
using VVI = vector<VI>;
using VL = vector<LL>;
using VVL = vector<VL>;
using VD = vector<double>;
using VVD = vector<VD>;
using PII = pair<int, int>;
using PDD = pair<double, double>;
using PLL = pair<LL, LL>;
using VPII = vector<PII>;
template <typename T> using VT = vector<T>;
#define ALL(a) begin((a)), end((a))
#define RALL(a) rbegin((a)), rend((a))
#define SORT(a) sort(ALL((a)))
#define RSORT(a) sort(RALL((a)))
#define REVERSE(a) reverse(ALL((a)))
#define MP make_pair
#define FORE(a, b) for (auto &&a : (b))
#define FIND(s, e) ((s).find(e) != (s).end())
#define EB emplace_back
template <typename T> inline bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <typename T> inline bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}

const int INF = 1e9;
const int MOD = INF + 7;
const LL LLINF = 1e18;
const double EPS = 1e-9;

void init() {}

set<int> dp[55];
vector<int> freeday[35];
void solve(int n) {
  for (int i = 0; i < 35; i++) {
    freeday[i].clear();
  }
  for (int j = 0; j < 55; j++) {
    dp[j].clear();
  }
  for (int i = 0; i < n; i++) {
    int m;
    cin >> m;
    dp[i].insert(i);
    for (int j = 0; j < m; j++) {
      int b;
      cin >> b;
      freeday[b].emplace_back(i);
    }
  }
  for (int i = 0; i < 31; i++) {
    for (int j = 0; j < (int)freeday[i].size(); j++) {
      for (int k = 0; k < (int)freeday[i].size(); k++) {
        if (freeday[i][j] != freeday[i][k]) {
          dp[freeday[i][j]].insert(begin(dp[freeday[i][k]]),
                                   end(dp[freeday[i][k]]));
        }
      }
    }
    for (int j = 0; j < (int)freeday[i].size(); j++) {
      for (int k = 0; k < (int)freeday[i].size(); k++) {
        if (freeday[i][j] != freeday[i][k]) {
          dp[freeday[i][j]].insert(begin(dp[freeday[i][k]]),
                                   end(dp[freeday[i][k]]));
        }
      }
    }
    for (int j = 0; j < n; j++) {
      if (dp[j].size() == n) {
        cout << i << endl;
        return;
      }
    }
  }
  puts("-1");
}

signed main(void) {
  LL n, m, p, a, b, c, x, y, z, q;
  string s;
  bool f = false;
  init();
  while (cin >> n, n) {
    solve(n);
  }
}

Error: 0

Fixed submission:

#include <algorithm>
#include <bitset>
#include <cassert>
#include <climits>
#include <cmath>
#include <complex>
#include <cstddef>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <fstream>
#include <iomanip>
#include <iostream>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <tuple>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

using namespace std;
#define REP(i, n) for (int(i) = 0; (i) < (n); (i)++)
#define FOR(i, a, b) for (int(i) = (a); (i) < (b); (i)++)
#define RREP(i, a) for (int(i) = (a)-1; (i) >= 0; (i)--)
#define FORR(i, a, b) for (int(i) = (a)-1; (i) >= (b); (i)--)
#define DEBUG(C) cerr << #C << " = " << C << endl;
using LL = long long;
using VI = vector<int>;
using VVI = vector<VI>;
using VL = vector<LL>;
using VVL = vector<VL>;
using VD = vector<double>;
using VVD = vector<VD>;
using PII = pair<int, int>;
using PDD = pair<double, double>;
using PLL = pair<LL, LL>;
using VPII = vector<PII>;
template <typename T> using VT = vector<T>;
#define ALL(a) begin((a)), end((a))
#define RALL(a) rbegin((a)), rend((a))
#define SORT(a) sort(ALL((a)))
#define RSORT(a) sort(RALL((a)))
#define REVERSE(a) reverse(ALL((a)))
#define MP make_pair
#define FORE(a, b) for (auto &&a : (b))
#define FIND(s, e) ((s).find(e) != (s).end())
#define EB emplace_back
template <typename T> inline bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <typename T> inline bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}

const int INF = 1e9;
const int MOD = INF + 7;
const LL LLINF = 1e18;
const double EPS = 1e-9;

void init() {}

set<int> dp[55];
vector<int> freeday[35];
void solve(int n) {
  for (int i = 0; i < 35; i++) {
    freeday[i].clear();
  }
  for (int j = 0; j < 55; j++) {
    dp[j].clear();
  }
  for (int i = 0; i < n; i++) {
    int m;
    cin >> m;
    dp[i].insert(i);
    for (int j = 0; j < m; j++) {
      int b;
      cin >> b;
      freeday[b].emplace_back(i);
    }
  }
  for (int i = 0; i < 31; i++) {
    for (int j = 0; j < (int)freeday[i].size(); j++) {
      for (int k = 0; k < (int)freeday[i].size(); k++) {
        if (freeday[i][j] != freeday[i][k]) {
          // DEBUG(freeday[i][j])DEBUG(freeday[i][k])
          dp[freeday[i][j]].insert(begin(dp[freeday[i][k]]),
                                   end(dp[freeday[i][k]]));
        }
      }
    }
    for (int j = 0; j < (int)freeday[i].size(); j++) {
      for (int k = 0; k < (int)freeday[i].size(); k++) {
        if (freeday[i][j] != freeday[i][k]) {
          // DEBUG(freeday[i][j])DEBUG(freeday[i][k])
          dp[freeday[i][j]].insert(begin(dp[freeday[i][k]]),
                                   end(dp[freeday[i][k]]));
        }
      }
    }
    for (int j = 0; j < n; j++) {
      if (dp[j].size() == n) {
        cout << i << endl;
        return;
      }
    }
  }
  assert(false);
}

signed main(void) {
  LL n, m, p, a, b, c, x, y, z, q;
  string s;
  bool f = false;
  init();
  while (cin >> n, n) {
    solve(n);
  }
}