Problem p02728 (C++) — buggy submission, verdict: Runtime Error

#include <algorithm>
#include <bits/stdc++.h>
#include <cstdio>
#include <iostream>
#include <map>
#include <string>
#include <vector>
using namespace std;
#define rep(i, x) for (ll i = 0; i < (ll)(x); i++)
#define rrep(i, x) for (ll i = (ll)(x)-1; 0 <= i; i--)
#define reps(i, x) for (ll i = 1; i < (ll)(x) + 1; i++)
#define rreps(i, x) for (ll i = (ll)(x); 1 <= i; i--)
#define debug(x) cerr << #x << ": " << (x) << "\\n";
#define all(x) (x).begin(), (x).end()
typedef long long ll;
typedef long double ld;
typedef pair<int, int> P;
typedef pair<ll, ll> Pll;
typedef vector<ll> vl;
typedef vector<vector<ll>> vvl;
typedef vector<vector<vector<ll>>> vvvl;
const ll INF = numeric_limits<ll>::max() / 4;
const int n_max = 2e5 + 10;

template <std::int_fast64_t Modulus> class modint {
  using i64 = int_fast64_t;

public:
  i64 a;

  constexpr modint(const i64 x = 0) noexcept {
    this->a = x % Modulus;
    if (a < 0) {
      a += Modulus;
    }
  }
  // constexpr i64 &value() const noexcept {return a;}
  constexpr const i64 &value() const noexcept { return a; }
  constexpr modint operator+(const modint rhs) const noexcept {
    return modint(*this) += rhs;
  }
  constexpr modint operator-(const modint rhs) const noexcept {
    return modint(*this) -= rhs;
  }
  constexpr modint operator*(const modint rhs) const noexcept {
    return modint(*this) *= rhs;
  }
  constexpr modint operator/(const modint rhs) const noexcept {
    return modint(*this) /= rhs;
  }
  constexpr modint &operator+=(const modint rhs) noexcept {
    a += rhs.a;
    if (a >= Modulus) {
      a -= Modulus;
    }
    return *this;
  }
  constexpr modint &operator-=(const modint rhs) noexcept {
    if (a < rhs.a) {
      a += Modulus;
    }
    a -= rhs.a;
    return *this;
  }
  constexpr modint &operator*=(const modint rhs) noexcept {
    a = a * rhs.a % Modulus;
    return *this;
  }
  constexpr modint &operator/=(modint rhs) noexcept {
    i64 a_ = rhs.a, b = Modulus, u = 1, v = 0;
    while (b) {
      i64 t = a_ / b;
      a_ -= t * b;
      swap(a_, b);
      u -= t * v;
      swap(u, v);
    }
    a = a * u % Modulus;
    if (a < 0)
      a += Modulus;
    return *this;
  }

  // 自前実装
  constexpr bool operator==(const modint rhs) noexcept { return a == rhs.a; }
  constexpr bool operator!=(const modint rhs) noexcept { return a != rhs.a; }
  constexpr bool operator>(const modint rhs) noexcept { return a > rhs.a; }
  constexpr bool operator>=(const modint rhs) noexcept { return a >= rhs.a; }
  constexpr bool operator<(const modint rhs) noexcept { return a < rhs.a; }
  constexpr bool operator<=(const modint rhs) noexcept { return a <= rhs.a; }
  constexpr modint &operator++() noexcept { return (*this) += modint(1); }
  constexpr modint operator++(int) {
    modint tmp(*this);
    operator++();
    return tmp;
  }
  constexpr modint &operator--() noexcept { return (*this) -= modint(1); }
  constexpr modint operator--(int) {
    modint tmp(*this);
    operator--();
    return tmp;
  }
  template <typename T>
  friend constexpr modint modpow(const modint &mt, T n) noexcept {
    if (n < 0) {
      modint t = (modint(1) / mt);
      return modpow(t, -n);
    }
    modint res = 1, tmp = mt;
    while (n) {
      if (n & 1)
        res *= tmp;
      tmp *= tmp;
      n /= 2;
    }
    return res;
  }
};

const ll MOD = 1e9 + 7;
using mint = modint<MOD>;
// 標準入出力対応
std::ostream &operator<<(std::ostream &out, const modint<MOD> &m) {
  out << m.a;
  return out;
}
std::istream &operator>>(std::istream &in, modint<MOD> &m) {
  ll a;
  in >> a;
  m = mint(a);
  return in;
}

void print() { cout << endl; }

template <class Head, class... Tail> void print(Head &&head, Tail &&...tail) {
  cout << head;
  if (sizeof...(tail) != 0)
    cout << ' ';
  print(forward<Tail>(tail)...);
}

template <class T> void print(vector<T> &vec) {
  for (auto &a : vec) {
    cout << a;
    if (&a != &vec.back())
      cout << ' ';
  }
  cout << endl;
}

template <class T> void print(vector<vector<T>> &df) {
  for (auto &vec : df) {
    print(vec);
  }
}

template <class T, class U> void print(pair<T, U> &p) {
  print(p.first, p.second);
}

// modintが必要
// modintによる実装
const int MAX = 1e6;
vector<mint> fac(MAX);
void COMinit() {
  fac[0] = 1;
  reps(i, MAX - 1) { fac[i] = fac[i - 1] * mint(i); }
}

mint COM(ll n, ll k) {
  if (n < k)
    return (mint)0;
  if (n < 0 || k < 0)
    return (mint)0;
  return fac[n] / (fac[k] * fac[n - k]);
}

// 木の上のトポロジカルソート
// 適当な根から有向であるとみなしてBFS
vector<ll> tree_topo(vvl &graph, ll root) {
  // const ll n_max = 2e5+10;
  bitset<n_max> bs(0);
  vector<ll> ans;
  queue<ll> que;
  que.emplace(root);
  bs[root] = 1;
  while (!que.empty()) {
    auto f = que.front();
    que.pop();
    ans.emplace_back(f);
    for (auto &to : graph[f]) {
      if (bs[to])
        continue;
      bs[to] = 1;
      que.emplace(to);
    }
  }
  return ans;
}

vector<ll> par(n_max);
bitset<n_max> used(0);
void dfs(vvl &graph, ll pos) {
  for (auto &to : graph[pos]) {
    if (used[to])
      continue;
    par[to] = pos;
    used[to] = 1;
    dfs(graph, to);
  }
}

int main() {

  ll n;
  cin >> n;
  vector<vector<ll>> graph(n);
  rep(i, n - 1) {
    ll a, b;
    cin >> a >> b;
    a--;
    b--;
    graph[a].emplace_back(b);
    graph[b].emplace_back(a);
  }

  vector<ll> topo = tree_topo(graph, 0);
  // vector<ll> rev_topo = tree_topo(graph, topo.back());

  // print(topo);
  // print(rev_topo);

  auto f = [&](vector<ll> &topo) {
    vector<ll> part(n, 0);
    ll temp;
    rrep(i, n) {
      temp = 0;
      for (auto &to : graph[topo[i]])
        temp += part[to];
      part[topo[i]] = temp + 1;
    };
    return part;
  };
  vector<ll> part = f(topo);
  // print(part);
  // print(rev_part);

  vector<mint> vec(n);
  COMinit();
  rep(i, n) {
    mint t = fac[n - 1];
    ll pos = topo[i];
    for (auto &to : graph[pos])
      if (part[to] < part[pos])
        t /= fac[part[to]];
    t /= fac[n - part[pos]];
    vec[pos] = t;
  }
  // print(vec);

  vector<mint> dp1(n), dp2(n, 0);
  rrep(i, n) {
    ll pos = topo[i];
    mint t = fac[part[pos] - 1];
    for (auto &to : graph[pos])
      if (part[to] < part[pos]) {
        t /= fac[part[to]];
        t *= dp1[to];
      }
    dp1[pos] = t;
  }
  used[0] = 1;
  par[0] = -1;
  dfs(graph, 0);
  dp2[0] = 1;
  rep(i, n) {
    ll pos = topo[i];
    mint t = 1;
    for (auto &to : graph[pos]) {
      if (part[to] > part[pos])
        continue;
      t *= dp1[to];
      t /= fac[part[to]];
    }
    if (par[pos] != -1) {
      t *= dp2[pos];
      t /= fac[n - part[pos]];
    }

    for (auto &to : graph[pos]) {
      if (part[to] > part[pos])
        continue;
      dp2[to] = t / dp1[to];
      dp2[to] *= fac[n - part[to] - 1] * fac[part[to]];
    }
  }
  // print(dp1);print(dp2);
  // rep(i,n)cout << par[i] << " ";
  // cout << endl;
  vector<mint> ans(n);
  rep(i, n) {
    ll pos = topo[i];
    mint t = vec[pos];
    for (auto &to : graph[pos]) {
      if (part[to] > part[pos])
        t *= dp2[pos];
      else
        t *= dp1[to];
    }
    ans[pos] = t;
  }
  // debug(n_max);
  print(ans);
}

Error: 0
n_max: 200010


Fixed submission:

#include <algorithm>
#include <bits/stdc++.h>
#include <cstdio>
#include <iostream>
#include <map>
#include <string>
#include <vector>
using namespace std;
#define rep(i, x) for (ll i = 0; i < (ll)(x); i++)
#define rrep(i, x) for (ll i = (ll)(x)-1; 0 <= i; i--)
#define reps(i, x) for (ll i = 1; i < (ll)(x) + 1; i++)
#define rreps(i, x) for (ll i = (ll)(x); 1 <= i; i--)
#define debug(x) cerr << #x << ": " << (x) << "\\n";
#define all(x) (x).begin(), (x).end()
typedef long long ll;
typedef long double ld;
typedef pair<int, int> P;
typedef pair<ll, ll> Pll;
typedef vector<ll> vl;
typedef vector<vector<ll>> vvl;
typedef vector<vector<vector<ll>>> vvvl;
const ll INF = numeric_limits<ll>::max() / 4;
const int n_max = 2e5 + 10;

template <std::int_fast64_t Modulus> class modint {
  using i64 = int_fast64_t;

public:
  i64 a;

  constexpr modint(const i64 x = 0) noexcept {
    this->a = x % Modulus;
    if (a < 0) {
      a += Modulus;
    }
  }
  // constexpr i64 &value() const noexcept {return a;}
  constexpr const i64 &value() const noexcept { return a; }
  constexpr modint operator+(const modint rhs) const noexcept {
    return modint(*this) += rhs;
  }
  constexpr modint operator-(const modint rhs) const noexcept {
    return modint(*this) -= rhs;
  }
  constexpr modint operator*(const modint rhs) const noexcept {
    return modint(*this) *= rhs;
  }
  constexpr modint operator/(const modint rhs) const noexcept {
    return modint(*this) /= rhs;
  }
  constexpr modint &operator+=(const modint rhs) noexcept {
    a += rhs.a;
    if (a >= Modulus) {
      a -= Modulus;
    }
    return *this;
  }
  constexpr modint &operator-=(const modint rhs) noexcept {
    if (a < rhs.a) {
      a += Modulus;
    }
    a -= rhs.a;
    return *this;
  }
  constexpr modint &operator*=(const modint rhs) noexcept {
    a = a * rhs.a % Modulus;
    return *this;
  }
  constexpr modint &operator/=(modint rhs) noexcept {
    i64 a_ = rhs.a, b = Modulus, u = 1, v = 0;
    while (b) {
      i64 t = a_ / b;
      a_ -= t * b;
      swap(a_, b);
      u -= t * v;
      swap(u, v);
    }
    a = a * u % Modulus;
    if (a < 0)
      a += Modulus;
    return *this;
  }

  // 自前実装
  constexpr bool operator==(const modint rhs) noexcept { return a == rhs.a; }
  constexpr bool operator!=(const modint rhs) noexcept { return a != rhs.a; }
  constexpr bool operator>(const modint rhs) noexcept { return a > rhs.a; }
  constexpr bool operator>=(const modint rhs) noexcept { return a >= rhs.a; }
  constexpr bool operator<(const modint rhs) noexcept { return a < rhs.a; }
  constexpr bool operator<=(const modint rhs) noexcept { return a <= rhs.a; }
  constexpr modint &operator++() noexcept { return (*this) += modint(1); }
  constexpr modint operator++(int) {
    modint tmp(*this);
    operator++();
    return tmp;
  }
  constexpr modint &operator--() noexcept { return (*this) -= modint(1); }
  constexpr modint operator--(int) {
    modint tmp(*this);
    operator--();
    return tmp;
  }
  template <typename T>
  friend constexpr modint modpow(const modint &mt, T n) noexcept {
    if (n < 0) {
      modint t = (modint(1) / mt);
      return modpow(t, -n);
    }
    modint res = 1, tmp = mt;
    while (n) {
      if (n & 1)
        res *= tmp;
      tmp *= tmp;
      n /= 2;
    }
    return res;
  }
};

const ll MOD = 1e9 + 7;
using mint = modint<MOD>;
// 標準入出力対応
std::ostream &operator<<(std::ostream &out, const modint<MOD> &m) {
  out << m.a;
  return out;
}
std::istream &operator>>(std::istream &in, modint<MOD> &m) {
  ll a;
  in >> a;
  m = mint(a);
  return in;
}

void print() { cout << endl; }

template <class Head, class... Tail> void print(Head &&head, Tail &&...tail) {
  cout << head;
  if (sizeof...(tail) != 0)
    cout << ' ';
  print(forward<Tail>(tail)...);
}

template <class T> void print(vector<T> &vec) {
  for (auto &a : vec) {
    cout << a;
    if (&a != &vec.back())
      cout << '\\n';
  }
  cout << endl;
}

template <class T> void print(vector<vector<T>> &df) {
  for (auto &vec : df) {
    print(vec);
  }
}

template <class T, class U> void print(pair<T, U> &p) {
  print(p.first, p.second);
}

// modintが必要
// modintによる実装
const int MAX = 1e6;
vector<mint> fac(MAX);
void COMinit() {
  fac[0] = 1;
  reps(i, MAX - 1) { fac[i] = fac[i - 1] * mint(i); }
}

mint COM(ll n, ll k) {
  if (n < k)
    return (mint)0;
  if (n < 0 || k < 0)
    return (mint)0;
  return fac[n] / (fac[k] * fac[n - k]);
}

// 木の上のトポロジカルソート
// 適当な根から有向であるとみなしてBFS
vector<ll> tree_topo(vvl &graph, ll root) {
  const ll n_max = 1e5 + 10;
  bitset<n_max> bs(0);
  vector<ll> ans;
  queue<ll> que;
  que.emplace(root);
  bs[root] = 1;
  while (!que.empty()) {
    auto f = que.front();
    que.pop();
    ans.emplace_back(f);
    for (auto &to : graph[f]) {
      if (bs[to])
        continue;
      bs[to] = 1;
      que.emplace(to);
    }
  }
  return ans;
}

vector<ll> par(n_max);
bitset<n_max> used(0);
void dfs(vvl &graph, ll pos) {
  for (auto &to : graph[pos]) {
    if (used[to])
      continue;
    par[to] = pos;
    used[to] = 1;
    dfs(graph, to);
  }
}

int main() {
  ll n;
  cin >> n;
  vector<vector<ll>> graph(n);
  rep(i, n - 1) {
    ll a, b;
    cin >> a >> b;
    a--;
    b--;
    graph[a].emplace_back(b);
    graph[b].emplace_back(a);
  }

  vector<ll> topo = tree_topo(graph, 0);
  // vector<ll> rev_topo = tree_topo(graph, topo.back());

  // print(topo);
  // print(rev_topo);

  auto f = [&](vector<ll> &topo) {
    vector<ll> part(n, 0);
    ll temp;
    rrep(i, n) {
      temp = 0;
      for (auto &to : graph[topo[i]])
        temp += part[to];
      part[topo[i]] = temp + 1;
    };
    return part;
  };
  vector<ll> part = f(topo);
  // print(part);
  // print(rev_part);

  vector<mint> vec(n);
  COMinit();
  rep(i, n) {
    mint t = fac[n - 1];
    ll pos = topo[i];
    for (auto &to : graph[pos])
      if (part[to] < part[pos])
        t /= fac[part[to]];
    t /= fac[n - part[pos]];
    vec[pos] = t;
  }
  // print(vec);

  vector<mint> dp1(n), dp2(n, 0);
  rrep(i, n) {
    ll pos = topo[i];
    mint t = fac[part[pos] - 1];
    for (auto &to : graph[pos])
      if (part[to] < part[pos]) {
        t /= fac[part[to]];
        t *= dp1[to];
      }
    dp1[pos] = t;
  }
  used[0] = 1;
  par[0] = -1;
  dfs(graph, 0);
  rep(i, n) {
    ll pos = topo[i];
    ll pa = par[pos];
    if (pa == -1) {
      dp2[pos] = 1;
      continue;
    }
    mint t = fac[n - part[pos] - 1];
    for (auto &to : graph[pa]) {
      if (to == pos)
        continue;
      if (part[to] > part[pa])
        continue;
      else {
        t *= dp1[to];
        t /= fac[part[to]];
      }
    }
    t *= dp2[pa];
    t /= fac[n - part[pa]];
    dp2[pos] = t;
  }
  // print(dp1);print(dp2);
  // rep(i,n)cout << par[i] << " ";
  // cout << endl;
  vector<mint> ans(n);
  rep(i, n) {
    ll pos = topo[i];
    mint t = vec[pos];
    for (auto &to : graph[pos]) {
      if (part[to] > part[pos])
        t *= dp2[pos];
      else
        t *= dp1[to];
    }
    ans[i] = t;
  }
  debug(n_max);
  print(ans);
}