Problem p02728 (C++) — buggy submission, verdict: Time Limit Exceeded

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll, ll> P;
struct edge {
  ll to, cost;
};
const int inf = 1 << 27;
const ll INF = 1LL << 60;
const int COMBMAX = 1001001;
const ll MOD = 1000000007;
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define eachdo(v, e) for (const auto &e : (v))
#define all(v) (v).begin(), (v).end()
#define lower_index(v, e)                                                      \\
  (ll) distance((v).begin(), lower_bound((v).begin(), (v).end(), e))
#define upper_index(v, e)                                                      \\
  (ll) distance((v).begin(), upper_bound((v).begin(), (v).end(), e))
ll mpow(ll a, ll n, ll mod = MOD) {
  ll res = 1;
  while (n > 0) {
    if (n & 1)
      res = res * a % mod;
    a = a * a % mod;
    n >>= 1;
  }
  return res;
}
void YesNo(bool j) {
  cout << (j ? "Yes" : "No") << endl;
  return;
}
void yesno(bool j) {
  cout << (j ? "yes" : "no") << endl;
  return;
}
template <class Head> void pt(Head &&head) {
  cout << head << endl;
  return;
}
template <class Head, class... Tail> void pt(Head &&head, Tail &&...tail) {
  cout << head << " ";
  pt(forward<Tail>(tail)...);
}
template <class T> void debug(T v) {
  rep(i, v.size()) cout << v[i] << " ";
  cout << endl;
}
template <class T> void debug2(T v) {
  rep(i, v.size()) {
    rep(j, v[i].size()) cout << v[i][j] << " ";
    cout << endl;
  }
}
template <class T1, class T2> ll bcount(T1 v, T2 a) {
  return upper_index(v, a) - lower_index(v, a);
}
template <class T1, class T2> inline bool chmin(T1 &a, T2 b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
template <class T1, class T2> inline bool chmax(T1 &a, T2 b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}

struct mint {
  ll x;
  mint(ll x = 0) : x((x % MOD + MOD) % MOD) {}
  mint &operator+=(const mint a) {
    if ((x += a.x) >= MOD)
      x -= MOD;
    return *this;
  }
  mint &operator-=(const mint a) {
    if ((x += MOD - a.x) >= MOD)
      x -= MOD;
    return *this;
  }
  mint &operator*=(const mint a) {
    (x *= a.x) %= MOD;
    return *this;
  }
  mint operator+(const mint a) const {
    mint res(*this);
    return res += a;
  }
  mint operator-(const mint a) const {
    mint res(*this);
    return res -= a;
  }
  mint operator*(const mint a) const {
    mint res(*this);
    return res *= a;
  }
  mint pow(ll t) const {
    if (!t)
      return 1;
    mint a = pow(t >> 1);
    a *= a;
    if (t & 1)
      a *= *this;
    return a;
  }
  mint inv() const { return pow(MOD - 2); }
  mint &operator/=(const mint a) { return (*this) *= a.inv(); }
  mint operator/(const mint a) const {
    mint res(*this);
    return res /= a;
  }
};

class combination {
public:
  vector<mint> fact, ifact;
  combination(int n) : fact(n + 1), ifact(n + 1) {
    assert(n < MOD);
    fact[0] = 1;
    for (int i = 1; i <= n; ++i)
      fact[i] = fact[i - 1] * i;
    ifact[n] = fact[n].inv();
    for (int i = n; i >= 1; --i)
      ifact[i - 1] = ifact[i] * i;
  }
  mint operator()(int n, int k) {
    if (k < 0 || k > n)
      return 0;
    if (COMBMAX < n) {
      mint ret = 1;
      for (ll i = 1; i <= k; i++) {
        ret *= (n - i + 1);
        ret /= i;
      }
      return ret;
    }
    return fact[n] * ifact[k] * ifact[n - k];
  }

  mint multi(ll n, ll sum, ll l, ll r) {
    ll m = r - l + 1;
    ll t = sum - n * (l - 1);
    mint ans = 0;
    for (ll k = 0; k <= (t - n) / m; k++) {
      ll sign = k % 2 == 0 ? 1 : -1;
      mint temp = this->operator()(n, k);
      temp *= this->operator()(n + (t - n - m * k - 1), t - n - m * k);
      temp *= sign;
      ans += temp;
    }
    return ans;
  }
} com(COMBMAX);

ll N;
vector<vector<ll>> g(200005, vector<ll>());
vector<pair<mint, ll>> DPpos(200005);
vector<pair<mint, ll>> DPngt(200005);
vector<bool> posVisited(200005, false);
vector<bool> negVisited(200005, false);

pair<mint, ll> dfs1(ll v, ll par = -1) {
  if (posVisited[v])
    return DPpos[v];
  mint ret = 1;
  ll siz = 0;
  eachdo(g[v], u) {
    if (u == par)
      continue;
    ret *= com(siz + dfs1(u, v).second, siz);
    ret *= dfs1(u, v).first;
    siz += dfs1(u, v).second;
  }
  siz += 1;
  DPpos[v] = make_pair(ret, siz);
  posVisited[v] = true;
  return DPpos[v];
}

void dfs2(ll v, ll par = -1) {
  // pt(v, par);
  if (par == -1) {
    DPngt[v] = DPpos[v];
  } else {
    mint part;
    ll partSize;
    tie(part, partSize) = DPngt[par];

    part /= com(N - 1, DPpos[v].second);
    part /= DPpos[v].first;

    partSize -= DPpos[v].second;

    mint ret;
    ll size;
    tie(ret, size) = DPpos[v];
    size--;
    ret *= com(N - 1, size);
    ret *= part;
    DPngt[v] = make_pair(ret, N);
  }
  eachdo(g[v], u) {
    if (par == u)
      continue;
    dfs2(u, v);
  }
  return;
}

int main() {
  cin >> N;
  rep(i, N - 1) {
    ll u, v;
    cin >> u >> v;
    g[--u].emplace_back(--v);
    g[v].emplace_back(u);
  }
  dfs1(0);
  dfs2(0);
  // rep(i, N) pt(DPpos[i].first.x, DPpos[i].second);
  rep(i, N) pt(DPngt[i].first.x);
  return 0;
}

Error: TLE

Fixed submission:

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll, ll> P;
struct edge {
  ll to, cost;
};
const int inf = 1 << 27;
const ll INF = 1LL << 60;
const int COMBMAX = 1001001;
const ll MOD = 1000000007;
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define eachdo(v, e) for (const auto &e : (v))
#define all(v) (v).begin(), (v).end()
#define lower_index(v, e)                                                      \\
  (ll) distance((v).begin(), lower_bound((v).begin(), (v).end(), e))
#define upper_index(v, e)                                                      \\
  (ll) distance((v).begin(), upper_bound((v).begin(), (v).end(), e))
ll mpow(ll a, ll n, ll mod = MOD) {
  ll res = 1;
  while (n > 0) {
    if (n & 1)
      res = res * a % mod;
    a = a * a % mod;
    n >>= 1;
  }
  return res;
}
void YesNo(bool j) {
  cout << (j ? "Yes" : "No") << endl;
  return;
}
void yesno(bool j) {
  cout << (j ? "yes" : "no") << endl;
  return;
}
template <class Head> void pt(Head &&head) {
  cout << head << endl;
  return;
}
template <class Head, class... Tail> void pt(Head &&head, Tail &&...tail) {
  cout << head << " ";
  pt(forward<Tail>(tail)...);
}
template <class T> void debug(T v) {
  rep(i, v.size()) cout << v[i] << " ";
  cout << endl;
}
template <class T> void debug2(T v) {
  rep(i, v.size()) {
    rep(j, v[i].size()) cout << v[i][j] << " ";
    cout << endl;
  }
}
template <class T1, class T2> ll bcount(T1 v, T2 a) {
  return upper_index(v, a) - lower_index(v, a);
}
template <class T1, class T2> inline bool chmin(T1 &a, T2 b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
template <class T1, class T2> inline bool chmax(T1 &a, T2 b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}

struct mint {
  ll x;
  mint(ll x = 0) : x((x % MOD + MOD) % MOD) {}
  mint &operator+=(const mint a) {
    if ((x += a.x) >= MOD)
      x -= MOD;
    return *this;
  }
  mint &operator-=(const mint a) {
    if ((x += MOD - a.x) >= MOD)
      x -= MOD;
    return *this;
  }
  mint &operator*=(const mint a) {
    (x *= a.x) %= MOD;
    return *this;
  }
  mint operator+(const mint a) const {
    mint res(*this);
    return res += a;
  }
  mint operator-(const mint a) const {
    mint res(*this);
    return res -= a;
  }
  mint operator*(const mint a) const {
    mint res(*this);
    return res *= a;
  }
  mint pow(ll t) const {
    if (!t)
      return 1;
    mint a = pow(t >> 1);
    a *= a;
    if (t & 1)
      a *= *this;
    return a;
  }
  mint inv() const { return pow(MOD - 2); }
  mint &operator/=(const mint a) { return (*this) *= a.inv(); }
  mint operator/(const mint a) const {
    mint res(*this);
    return res /= a;
  }
};

class combination {
public:
  vector<mint> fact, ifact;
  combination(int n) : fact(n + 1), ifact(n + 1) {
    assert(n < MOD);
    fact[0] = 1;
    for (int i = 1; i <= n; ++i)
      fact[i] = fact[i - 1] * i;
    ifact[n] = fact[n].inv();
    for (int i = n; i >= 1; --i)
      ifact[i - 1] = ifact[i] * i;
  }
  mint operator()(int n, int k) {
    if (k < 0 || k > n)
      return 0;
    if (COMBMAX < n) {
      mint ret = 1;
      for (ll i = 1; i <= k; i++) {
        ret *= (n - i + 1);
        ret /= i;
      }
      return ret;
    }
    return fact[n] * ifact[k] * ifact[n - k];
  }

  mint multi(ll n, ll sum, ll l, ll r) {
    ll m = r - l + 1;
    ll t = sum - n * (l - 1);
    mint ans = 0;
    for (ll k = 0; k <= (t - n) / m; k++) {
      ll sign = k % 2 == 0 ? 1 : -1;
      mint temp = this->operator()(n, k);
      temp *= this->operator()(n + (t - n - m * k - 1), t - n - m * k);
      temp *= sign;
      ans += temp;
    }
    return ans;
  }
} com(COMBMAX);

ll N;
vector<vector<ll>> g(200005, vector<ll>());
vector<pair<mint, ll>> DPpos(200005);
vector<bool> posVisited(200005);
vector<pair<mint, ll>> DPNgt(200005);

pair<mint, ll> dfs1(ll v, ll par = -1) {
  if (posVisited[v])
    return DPpos[v];
  mint ret = 1;
  ll siz = 0;
  eachdo(g[v], u) {
    if (u == par)
      continue;
    ret *= com(siz + dfs1(u, v).second, siz);
    ret *= dfs1(u, v).first;
    siz += dfs1(u, v).second;
  }
  siz += 1;
  DPpos[v] = make_pair(ret, siz);
  posVisited[v] = true;
  return DPpos[v];
}

pair<mint, ll> dfs2(ll v) { return make_pair(0, 0); }

int main() {
  cin >> N;
  rep(i, N - 1) {
    ll u, v;
    cin >> u >> v;
    g[--u].emplace_back(--v);
    g[v].emplace_back(u);
    // dfs2(0);
  }
  rep(i, N) {
    rep(j, N) posVisited[j] = false;
    dfs1(i);
    cout << DPpos[i].first.x << endl;
  }
  return 0;
}