Problem p03911 (C++)

Buggy submission (status: Runtime Error):
/**
 * code generated by JHelper
 * More info: https://github.com/AlexeyDmitriev/JHelper
 * @author champon
 */

#include <fstream>
#include <iostream>

#include <bits/stdc++.h>
#define se cout << "test ok" << endl;
#define sp << " " <<
#define enl "\n";
using namespace std;
using ll = long long;
using ld = long double;
ll mod = ll(1e9) + 7;
ll inf = ll(1e18);
void bl(bool b, ostream &out = cout) { out << (b ? "Yes" : "No") << endl; }
void bl2(bool b, ostream &out = cout) { out << (b ? "YES" : "NO") << endl; }
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;
}
template <typename A, size_t N, typename T>
void Fill(A (&array)[N], const T &val) {
  fill((T *)array, (T *)(array + N), val);
}
int dx[] = {1, 0, -1, 0, 1, -1, 1, -1};
int dy[] = {0, 1, 0, -1, 1, -1, -1, 1};

#ifndef INCLUDE_DEBUG_HPP
#define INCLUDE_DEBUG_HPP

#include <iostream>
#include <map>
#include <vector>
using namespace std;

namespace dbg {
using ll = long long;

class Debug {
public:
  Debug() {}
  template <typename T> void vd(vector<T> vec);
  template <typename T> void vd2(vector<vector<T>> vec);
  template <typename T> void ad(T *arr, ll n);
  template <typename T, size_t N> void ad2(T (&arr)[N], ll n);
  template <typename T> void md(T mp);
};

template <typename T> void Debug::vd(vector<T> vec) {
  for (auto vv : vec)
    cout << vv << " ";
  cout << endl;
}

template <typename T> void Debug::vd2(vector<vector<T>> vec) {
  for (auto vv : vec)
    for (auto vvv : vv)
      cout << vvv << " ";
  cout << endl;
}

template <typename T> void Debug::ad(T *arr, ll n) {
  for (int i = 0; i <= n; i++)
    cout << arr[i] << " ";
  cout << endl;
}

template <typename T, size_t N> void Debug::ad2(T (&arr)[N], ll n) {
  for (int i = 0; i <= N; i++)
    for (int j = 0; j <= n; j++)
      cout << arr[i][j] << " ";
  cout << endl;
}

template <typename T> void Debug::md(T mp) {
  cout << "key : value" << endl;
  for (auto const &m : mp)
    cout << m.first << " : " << m.second << endl;
  cout << endl;
}

} // namespace dbg

#endif // INCLUDE_DEBUG_HPP

using dbg::Debug;
Debug debug;

#ifndef DEFINE_UNIONFIND_HPP
#define DEFINE_UNIONFIND_HPP

#include <numeric>

using namespace std;

namespace unionfind {

using ll = long long;

class UnionFind {
public:
  ll n;
  vector<ll> par;
  vector<ll> rank;
  vector<ll> size;

  UnionFind(int n);
  ll find(ll x);
  void unite(ll x, ll y);
  bool same(ll x, ll y);
  ll getsize(ll x);
  int rootCount();
};

UnionFind::UnionFind(int n) : n(n), par(n, 0), rank(n, 0), size(n, 1) {
  iota(par.begin(), par.end(), 0);
}

ll UnionFind::find(ll x) {
  if (par[x] == x)
    return x;
  else
    return par[x] = find(par[x]);
}

void UnionFind::unite(ll x, ll y) {
  x = find(x);
  y = find(y);
  if (x == y)
    return;
  if (rank[x] < rank[y]) {
    par[x] = y;
    size[y] += size[x];
  } else {
    par[y] = x;
    size[x] += size[y];
    if (rank[x] == rank[y])
      rank[x]++;
  }
}

bool UnionFind::same(ll x, ll y) { return find(x) == find(y); }

// get size of tree
ll UnionFind::getsize(ll x) { return size[find(x)]; }

// get the number of roots
int UnionFind::rootCount() {
  int cnt = 0;
  for (int i = 0; i < n; i++) {
    if (i == par[i])
      cnt++;
  }
  return cnt;
}

// verify
// https://atc001.contest.atcoder.jp/tasks/unionfind_a

} // namespace unionfind

#endif // DEFINE_UNIONFIND_HPP
using unionfind::UnionFind;

class CInterpretation {
public:
  void solve(std::istream &in, std::ostream &out) {
    int n, m;
    in >> n >> m;
    UnionFind uf(n + m);
    for (int i = 0; i < n; i++) {
      int k, l;
      in >> k;
      for (int j = 0; j < k; j++) {
        in >> l;
        uf.unite(--l, m + i);
      }
    }

    bool flg = true;
    for (int i = 0; i < n; i++) {
      if (!uf.same(m + i, m + i + 1))
        flg = false;
    }

    bl2(flg, out);
  }
};

int main() {
  CInterpretation solver;
  std::istream &in(std::cin);
  std::ostream &out(std::cout);
  solver.solve(in, out);
  return 0;
}


Fixed submission:
/**
 * code generated by JHelper
 * More info: https://github.com/AlexeyDmitriev/JHelper
 * @author champon
 */

#include <fstream>
#include <iostream>

#include <bits/stdc++.h>
#define se cout << "test ok" << endl;
#define sp << " " <<
#define enl "\n";
using namespace std;
using ll = long long;
using ld = long double;
ll mod = ll(1e9) + 7;
ll inf = ll(1e18);
void bl(bool b, ostream &out = cout) { out << (b ? "Yes" : "No") << endl; }
void bl2(bool b, ostream &out = cout) { out << (b ? "YES" : "NO") << endl; }
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;
}
template <typename A, size_t N, typename T>
void Fill(A (&array)[N], const T &val) {
  fill((T *)array, (T *)(array + N), val);
}
int dx[] = {1, 0, -1, 0, 1, -1, 1, -1};
int dy[] = {0, 1, 0, -1, 1, -1, -1, 1};

#ifndef INCLUDE_DEBUG_HPP
#define INCLUDE_DEBUG_HPP

#include <iostream>
#include <map>
#include <vector>
using namespace std;

namespace dbg {
using ll = long long;

class Debug {
public:
  Debug() {}
  template <typename T> void vd(vector<T> vec);
  template <typename T> void vd2(vector<vector<T>> vec);
  template <typename T> void ad(T *arr, ll n);
  template <typename T, size_t N> void ad2(T (&arr)[N], ll n);
  template <typename T> void md(T mp);
};

template <typename T> void Debug::vd(vector<T> vec) {
  for (auto vv : vec)
    cout << vv << " ";
  cout << endl;
}

template <typename T> void Debug::vd2(vector<vector<T>> vec) {
  for (auto vv : vec)
    for (auto vvv : vv)
      cout << vvv << " ";
  cout << endl;
}

template <typename T> void Debug::ad(T *arr, ll n) {
  for (int i = 0; i <= n; i++)
    cout << arr[i] << " ";
  cout << endl;
}

template <typename T, size_t N> void Debug::ad2(T (&arr)[N], ll n) {
  for (int i = 0; i <= N; i++)
    for (int j = 0; j <= n; j++)
      cout << arr[i][j] << " ";
  cout << endl;
}

template <typename T> void Debug::md(T mp) {
  cout << "key : value" << endl;
  for (auto const &m : mp)
    cout << m.first << " : " << m.second << endl;
  cout << endl;
}

} // namespace dbg

#endif // INCLUDE_DEBUG_HPP

using dbg::Debug;
Debug debug;

#ifndef DEFINE_UNIONFIND_HPP
#define DEFINE_UNIONFIND_HPP

#include <numeric>

using namespace std;

namespace unionfind {

using ll = long long;

class UnionFind {
public:
  ll n;
  vector<ll> par;
  vector<ll> rank;
  vector<ll> size;

  UnionFind(int n);
  ll find(ll x);
  void unite(ll x, ll y);
  bool same(ll x, ll y);
  ll getsize(ll x);
  int rootCount();
};

UnionFind::UnionFind(int n) : n(n), par(n, 0), rank(n, 0), size(n, 1) {
  iota(par.begin(), par.end(), 0);
}

ll UnionFind::find(ll x) {
  if (par[x] == x)
    return x;
  else
    return par[x] = find(par[x]);
}

void UnionFind::unite(ll x, ll y) {
  x = find(x);
  y = find(y);
  if (x == y)
    return;
  if (rank[x] < rank[y]) {
    par[x] = y;
    size[y] += size[x];
  } else {
    par[y] = x;
    size[x] += size[y];
    if (rank[x] == rank[y])
      rank[x]++;
  }
}

bool UnionFind::same(ll x, ll y) { return find(x) == find(y); }

// get size of tree
ll UnionFind::getsize(ll x) { return size[find(x)]; }

// get the number of roots
int UnionFind::rootCount() {
  int cnt = 0;
  for (int i = 0; i < n; i++) {
    if (i == par[i])
      cnt++;
  }
  return cnt;
}

// verify
// https://atc001.contest.atcoder.jp/tasks/unionfind_a

} // namespace unionfind

#endif // DEFINE_UNIONFIND_HPP
using unionfind::UnionFind;

class CInterpretation {
public:
  void solve(std::istream &in, std::ostream &out) {
    int n, m;
    in >> n >> m;
    UnionFind uf(n + m);
    for (int i = 0; i < n; i++) {
      int k, l;
      in >> k;
      for (int j = 0; j < k; j++) {
        in >> l;
        uf.unite(--l, m + i);
      }
    }

    bool flg = true;
    for (int i = 0; i < n - 1; i++) {
      if (!uf.same(m + i, m + i + 1))
        flg = false;
    }

    bl2(flg, out);
  }
};

int main() {
  CInterpretation solver;
  std::istream &in(std::cin);
  std::ostream &out(std::cout);
  solver.solve(in, out);
  return 0;
}