Problem p02574 (C++) — buggy submission, verdict: Runtime Error

// include
//------------------------------------------
#include <bits/stdc++.h>
using namespace std;

// typedef
//------------------------------------------
using LL = int64_t;
using VL = vector<LL>;
using VVL = vector<VL>;
using VS = vector<string>;
using PLL = pair<LL, LL>;

// container util
//------------------------------------------
#define whole(f, x, ...)                                                       \\
  ([&](decltype((x)) whole) {                                                  \\
    return (f)(begin(whole), end(whole), ##__VA_ARGS__);                       \\
  })(x)
#define rwhole(f, x, ...)                                                      \\
  ([&](decltype((x)) whole) {                                                  \\
    return (f)(rbegin(whole), rend(whole), ##__VA_ARGS__);                     \\
  })(x)
#define EACH(i, c)                                                             \\
  for (decltype((c).begin()) i = (c).begin(); i != (c).end(); ++i)
#define EXIST(s, e) ((s).find(e) != (s).end())
#define ALL(x) ::std::begin(x), ::std::end(x)
#define RALL(x) ::std::rbegin(x), ::std::rend(x)
#define SORT(c) whole(sort, c)
#define RSORT(c) rwhole(sort, c)

// constant
//--------------------------------------------
constexpr double EPS = 1e-10;
constexpr double PI = 3.14159265358979323846;
constexpr int MOD = 1000000007;

// grid
//--------------------------------------------
VL dx = {0, 1, 0, -1};
VL dy = {1, 0, -1, 0};
VL dx2 = {-1, 0, 1, -1, 1, -1, 0, 1};
VL dy2 = {-1, -1, -1, 0, 0, 1, 1, 1};

// debug
//--------------------------------------------
#define dump(x) cerr << #x << " = " << (x) << endl;
#define debug(x)                                                               \\
  cerr << #x << " = " << (x) << " (L" << __LINE__ << ")"                       \\
       << " " << __FILE__ << endl;

// IO accelerate
//--------------------------------------------
struct InitIO {
  InitIO() {
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);
    cout << fixed << setprecision(30);
  }
} init_io;

// template
//--------------------------------------------
//  declaretion
template <typename T> istream &operator>>(istream &is, vector<T> &vec);
template <typename T1, typename T2>
ostream &operator<<(ostream &os, const pair<T1, T2> &p);
template <typename T> ostream &operator<<(ostream &os, const vector<T> &vec);
template <typename T>
ostream &operator<<(ostream &os, const vector<vector<T>> &vv);
template <typename T> vector<T> make_v(size_t a);
template <typename T, typename... Ts> auto make_v(size_t a, Ts... ts);
template <typename T, typename V>
typename enable_if<is_class<T>::value == 0>::type fill_v(T &t, const V &v);
template <typename T, typename V>
typename enable_if<is_class<T>::value != 0>::type fill_v(T &t, const V &v);

// implementation
template <typename T> istream &operator>>(istream &is, vector<T> &vec) {
  for (T &x : vec)
    is >> x;
  return is;
}
template <typename T1, typename T2>
ostream &operator<<(ostream &os, const pair<T1, T2> &p) {
  os << p.first << "," << p.second;
  return os;
}
template <typename T> ostream &operator<<(ostream &os, const vector<T> &vec) {
  for (int i = 0; i < vec.size(); i++) {
    os << vec[i] << (i + 1 == vec.size() ? "" : "\\t");
  }
  return os;
}
template <typename T>
ostream &operator<<(ostream &s, const vector<vector<T>> &vv) {
  for (int i = 0; i < vv.size(); ++i) {
    s << vv[i] << endl;
  }
  return s;
}

// 多重vector
// auto dp=make_v<int>(4,h,w) みたいに使える
template <typename T> vector<T> make_v(size_t a) { return vector<T>(a); }

template <typename T, typename... Ts> auto make_v(size_t a, Ts... ts) {
  return vector<decltype(make_v<T>(ts...))>(a, make_v<T>(ts...));
}

// 多重vectorのためのfill
// fill_v(dp,0) みたいに使える
template <typename T, typename V>
typename enable_if<is_class<T>::value == 0>::type fill_v(T &t, const V &v) {
  t = v;
}

template <typename T, typename V>
typename enable_if<is_class<T>::value != 0>::type fill_v(T &t, const V &v) {
  for (auto &e : t)
    fill_v(e, v);
}

template <class T, class U> void chmax(T &a, U b) {
  if (a < b)
    a = b;
}
template <class T, class U> void chmin(T &a, U b) {
  if (b < a)
    a = b;
}
template <typename T> T gcd(T a, T b) { return b ? gcd(b, a % b) : a; }
template <typename T> T lcm(T a, T b) { return a / gcd(a, b) * b; }

// main code

// 数列Aに格納された数の素因数分解を高速に行う
// 計算量 O(Amaxloglog(Amax))
template <class T> auto fastFactorize(T &A) {
  LL M = *(max_element(A.begin(), A.end())) + 1;
  vector<int64_t> D(M, 0);
  D[1] = 1;
  for (int i = 2; i < M; i++) {
    if (D[i] == 0) {
      for (int j = i; j < M; j += i) {
        D[j] = i;
      }
    }
  }
  vector<map<int64_t, int>> ret(A.size());
  for (int i = 0; i < A.size(); i++) {
    auto a = A[i];
    while (D[a] != a) {
      ret[i][D[a]]++;
      a /= D[a];
    }
    ret[i][a]++;
  }
  return ret;
}

int main(int argc, char *argv[]) {
  LL n;
  cin >> n;
  VL a(n);
  cin >> a;
  LL g = a[0];
  for (int i = 1; i < n; i++) {
    g = gcd(g, a[i]);
  }
  if (g > 1) {
    cout << "not coprime" << endl;
    return 0;
  }
  auto fac = fastFactorize(a);
  vector<bool> vb(1000001, false);
  for (int i = 0; i < n; i++) {
    if (a[i] == 1) {
      continue;
    }
    for (auto [key, val] : fac[i]) {
      if (vb[key]) {
        cout << "setwise coprime" << endl;
        return 0;
      }
      vb[key] = true;
    }
  }
  cout << "pairwise coprime" << endl;
  return 0;
}

Error: WA

Fixed submission:

// include
//------------------------------------------
#include <bits/stdc++.h>
using namespace std;

// typedef
//------------------------------------------
using LL = int64_t;
using VL = vector<LL>;
using VVL = vector<VL>;
using VS = vector<string>;
using PLL = pair<LL, LL>;

// container util
//------------------------------------------
#define whole(f, x, ...)                                                       \\
  ([&](decltype((x)) whole) {                                                  \\
    return (f)(begin(whole), end(whole), ##__VA_ARGS__);                       \\
  })(x)
#define rwhole(f, x, ...)                                                      \\
  ([&](decltype((x)) whole) {                                                  \\
    return (f)(rbegin(whole), rend(whole), ##__VA_ARGS__);                     \\
  })(x)
#define EACH(i, c)                                                             \\
  for (decltype((c).begin()) i = (c).begin(); i != (c).end(); ++i)
#define EXIST(s, e) ((s).find(e) != (s).end())
#define ALL(x) ::std::begin(x), ::std::end(x)
#define RALL(x) ::std::rbegin(x), ::std::rend(x)
#define SORT(c) whole(sort, c)
#define RSORT(c) rwhole(sort, c)

// constant
//--------------------------------------------
constexpr double EPS = 1e-10;
constexpr double PI = 3.14159265358979323846;
constexpr int MOD = 1000000007;

// grid
//--------------------------------------------
VL dx = {0, 1, 0, -1};
VL dy = {1, 0, -1, 0};
VL dx2 = {-1, 0, 1, -1, 1, -1, 0, 1};
VL dy2 = {-1, -1, -1, 0, 0, 1, 1, 1};

// debug
//--------------------------------------------
#define dump(x) cerr << #x << " = " << (x) << endl;
#define debug(x)                                                               \\
  cerr << #x << " = " << (x) << " (L" << __LINE__ << ")"                       \\
       << " " << __FILE__ << endl;

// IO accelerate
//--------------------------------------------
struct InitIO {
  InitIO() {
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);
    cout << fixed << setprecision(30);
  }
} init_io;

// template
//--------------------------------------------
//  declaretion
template <typename T> istream &operator>>(istream &is, vector<T> &vec);
template <typename T1, typename T2>
ostream &operator<<(ostream &os, const pair<T1, T2> &p);
template <typename T> ostream &operator<<(ostream &os, const vector<T> &vec);
template <typename T>
ostream &operator<<(ostream &os, const vector<vector<T>> &vv);
template <typename T> vector<T> make_v(size_t a);
template <typename T, typename... Ts> auto make_v(size_t a, Ts... ts);
template <typename T, typename V>
typename enable_if<is_class<T>::value == 0>::type fill_v(T &t, const V &v);
template <typename T, typename V>
typename enable_if<is_class<T>::value != 0>::type fill_v(T &t, const V &v);

// implementation
template <typename T> istream &operator>>(istream &is, vector<T> &vec) {
  for (T &x : vec)
    is >> x;
  return is;
}
template <typename T1, typename T2>
ostream &operator<<(ostream &os, const pair<T1, T2> &p) {
  os << p.first << "," << p.second;
  return os;
}
template <typename T> ostream &operator<<(ostream &os, const vector<T> &vec) {
  for (int i = 0; i < vec.size(); i++) {
    os << vec[i] << (i + 1 == vec.size() ? "" : "\\t");
  }
  return os;
}
template <typename T>
ostream &operator<<(ostream &s, const vector<vector<T>> &vv) {
  for (int i = 0; i < vv.size(); ++i) {
    s << vv[i] << endl;
  }
  return s;
}

// 多重vector
// auto dp=make_v<int>(4,h,w) みたいに使える
template <typename T> vector<T> make_v(size_t a) { return vector<T>(a); }

template <typename T, typename... Ts> auto make_v(size_t a, Ts... ts) {
  return vector<decltype(make_v<T>(ts...))>(a, make_v<T>(ts...));
}

// 多重vectorのためのfill
// fill_v(dp,0) みたいに使える
template <typename T, typename V>
typename enable_if<is_class<T>::value == 0>::type fill_v(T &t, const V &v) {
  t = v;
}

template <typename T, typename V>
typename enable_if<is_class<T>::value != 0>::type fill_v(T &t, const V &v) {
  for (auto &e : t)
    fill_v(e, v);
}

template <class T, class U> void chmax(T &a, U b) {
  if (a < b)
    a = b;
}
template <class T, class U> void chmin(T &a, U b) {
  if (b < a)
    a = b;
}
template <typename T> T gcd(T a, T b) { return b ? gcd(b, a % b) : a; }
template <typename T> T lcm(T a, T b) { return a / gcd(a, b) * b; }

// main code
struct UnionFind {
  // par[i]：データiが属する木の親の番号。i ==
  // par[i]のとき、データiは木の根ノードである
  vector<int> par;
  // sizes[i]：根ノードiの木に含まれるデータの数。iが根ノードでない場合は無意味な値となる
  vector<int> sizes;

  UnionFind(int n) : par(n), sizes(n, 1) {
    // 最初は全てのデータiがグループiに存在するものとして初期化
    for (int i = 0; i < n; i++)
      par[i] = i;
  }

  // データxが属する木の根を得る
  int find(int x) {
    if (x == par[x])
      return x;
    return par[x] = find(par[x]); // 根を張り替えながら再帰的に根ノードを探す
  }

  // 2つのデータx, yが属する木をマージする
  void unite(int x, int y) {
    // データの根ノードを得る
    x = find(x);
    y = find(y);
    // 既に同じ木に属しているならマージしない
    if (x == y)
      return;
    // xの木がyの木より大きくなるようにする
    if (sizes[x] < sizes[y])
      swap(x, y);
    // xがyの親になるように連結する
    par[y] = x;
    sizes[x] += sizes[y];
    // sizes[y] = 0;  // sizes[y]は無意味な値となるので0を入れておいてもよい
  }

  // 2つのデータx, yが属する木が同じならtrueを返す
  bool same(int x, int y) { return find(x) == find(y); }

  // データxが含まれる木の大きさを返す
  int size(int x) { return sizes[find(x)]; }
};

int main(int argc, char *argv[]) {
  LL n, m;
  cin >> n >> m;
  UnionFind uf(n);
  for (int i = 0; i < m; i++) {
    LL a, b;
    cin >> a >> b;
    a--;
    b--;
    uf.unite(a, b);
  }
  LL ans = 0;
  for (int i = 0; i < n; i++) {
    chmax(ans, uf.size(i));
  }
  cout << ans << endl;
  return 0;
}