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

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

#define li long long int
#define rep(i, to) for (li i = 0; i < ((li)(to)); i++)
#define repp(i, start, to) for (li i = (li)(start); i < ((li)(to)); i++)
#define pb push_back
#define sz(v) ((li)(v).size())
#define bgn(v) ((v).begin())
#define eend(v) ((v).end())
#define allof(v) (v).begin(), (v).end()
#define dodp(v, n) memset(v, (li)n, sizeof(v))
#define bit(n) (1ll << (li)(n))
#define mp(a, b) make_pair(a, b)
#define rin rep(i, n)
#define EPS 1e-12
#define ETOL 1e-8
#define MOD 1000000007
typedef pair<li, li> PI;

#define INF bit(60)

#define DBGP 1

#define idp if (DBGP)
#define F first
#define S second
#define p2(a, b) idp cout << a << "\\t" << b << endl
#define p3(a, b, c) idp cout << a << "\\t" << b << "\\t" << c << endl
#define p4(a, b, c, d)                                                         \\
  idp cout << a << "\\t" << b << "\\t" << c << "\\t" << d << endl
#define p5(a, b, c, d, e)                                                      \\
  idp cout << a << "\\t" << b << "\\t" << c << "\\t" << d << "\\t" << e << endl
#define p6(a, b, c, d, e, f)                                                   \\
  idp cout << a << "\\t" << b << "\\t" << c << "\\t" << d << "\\t" << e << "\\t"    \\
           << f << endl
#define p7(a, b, c, d, e, f, g)                                                \\
  idp cout << a << "\\t" << b << "\\t" << c << "\\t" << d << "\\t" << e << "\\t"    \\
           << f << "\\t" << g << endl
#define p8(a, b, c, d, e, f, g, h)                                             \\
  idp cout << a << "\\t" << b << "\\t" << c << "\\t" << d << "\\t" << e << "\\t"    \\
           << f << "\\t" << g << "\\t" << h << endl
#define p9(a, b, c, d, e, f, g, h, i)                                          \\
  idp cout << a << "\\t" << b << "\\t" << c << "\\t" << d << "\\t" << e << "\\t"    \\
           << f << "\\t" << g << "\\t" << h << "\\t" << i << endl
#define p10(a, b, c, d, e, f, g, h, i, j)                                      \\
  idp cout << a << "\\t" << b << "\\t" << c << "\\t" << d << "\\t" << e << "\\t"    \\
           << f << "\\t" << g << "\\t" << h << "\\t" << i << "\\t" << j << endl
#define foreach(it, v)                                                         \\
  for (__typeof((v).begin()) it = (v).begin(); it != (v).end(); ++it)
#define p2p(x) idp p2((x).F, (x).S)
#define dump(x, n)                                                             \\
  idp {                                                                        \\
    rep(i, n) { cout << x[i] << " "; }                                         \\
    puts("");                                                                  \\
  }
#define dump2(x, n)                                                            \\
  idp {                                                                        \\
    rep(i, n) { cout << "[" << x[i].F << " , " << x[i].S << "] "; }            \\
    puts("");                                                                  \\
  }
#define dumpi(x)                                                               \\
  idp {                                                                        \\
    foreach (it, x) {                                                          \\
      cout << (*it) << " ";                                                    \\
    }                                                                          \\
    puts("");                                                                  \\
  }
#define dumpi2(x)                                                              \\
  idp {                                                                        \\
    foreach (it, x) {                                                          \\
      cout << "[" << (it)->F << " , " << (it)->S << "] ";                      \\
    }                                                                          \\
    puts("");                                                                  \\
  }

#define read2d(a, w, h) rep(i, h) rep(j, w) cin >> a[i][j]
#define dump2d(a, w, h)                                                        \\
  rep(i, h) {                                                                  \\
    rep(j, w) cout << a[i][j] << " ";                                          \\
    puts("");                                                                  \\
  }

typedef pair<li, li> PI;

li fact_mod[200100];

inline void init() {
  fact_mod[0] = 1;
  fact_mod[1] = 1;
  repp(i, 2, 200100) { fact_mod[i] = (fact_mod[i - 1] * i) % MOD; }
}

inline li gcd(li a, li b) { return b != 0 ? gcd(b, a % b) : a; }
// a x + b y = gcd(a, b)
inline li extgcd(li a, li b, li &x, li &y) {
  li g = a;
  x = 1;
  y = 0;
  if (b != 0)
    g = extgcd(b, a % b, y, x), y -= (a / b) * x;
  return g;
}

inline li invMod(li a) {
  li x, y;
  if (extgcd(a, MOD, x, y) == 1)
    return (x + MOD) % MOD;
  else
    return 0; // unsolvable
}

inline li combi(li n, li k) {
  return (((fact_mod[n] * invMod(fact_mod[k])) % MOD) *
          invMod(fact_mod[n - k])) %
         MOD;
}

vector<li> edge[200100];

// {from, to} -> node_num, order_num
unordered_map<li, PI> m[200100];

inline PI calc(li from, li now) {
  li res = 1;
  li vnum = 1;
  li vvp = 1;
  for (auto &&next : edge[now]) {
    if (next == from) {
      continue;
    }
    if (m[next].count(now) == 0) {
      m[next][now] = calc(now, next);
    }
    PI tmp = m[next][now];
    res = (res * tmp.S) % MOD;
    vnum += tmp.F;
    vvp = (vvp * combi(vnum - 1, tmp.F)) % MOD;
  }

  res = (res * vvp) % MOD;
  if (from == -1) {
    for (auto &&next : edge[now]) {
      if (m[now].count(next) > 0) {
        continue;
      }
      // いっこダメだった場合を計算する
      PI tmp = m[next][now];
      li tres = res;
      tres = (tres * invMod(combi(vnum - 1, tmp.F))) % MOD;
      tres = (tres * invMod(m[next][now].S)) % MOD;
      m[now][next] = {vnum - tmp.F, tres};
    }
  }
  return {vnum, res};
}
int main() {
  init();
  li n;
  cin >> n;
  rep(i, n - 1) {
    li a, b;
    cin >> a >> b;
    a--;
    b--;
    edge[a].pb(b);
    edge[b].pb(a);
  }

  vector<PI> order;
  rin { order.pb({sz(edge[i]), i}); }
  sort(allof(order));
  reverse(allof(order));

  vector<li> res(n);
  rin { res[order[i].S] = calc(-1, order[i].S).S; }
  rin { cout << res[i] << endl; }

  return 0;
}

Error: TLE

Fixed submission:

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

#define li long long int
#define rep(i, to) for (li i = 0; i < ((li)(to)); i++)
#define repp(i, start, to) for (li i = (li)(start); i < ((li)(to)); i++)
#define pb push_back
#define sz(v) ((li)(v).size())
#define bgn(v) ((v).begin())
#define eend(v) ((v).end())
#define allof(v) (v).begin(), (v).end()
#define dodp(v, n) memset(v, (li)n, sizeof(v))
#define bit(n) (1ll << (li)(n))
#define mp(a, b) make_pair(a, b)
#define rin rep(i, n)
#define EPS 1e-12
#define ETOL 1e-8
#define MOD 1000000007
typedef pair<li, li> PI;

#define INF bit(60)

#define DBGP 1

#define idp if (DBGP)
#define F first
#define S second
#define p2(a, b) idp cout << a << "\\t" << b << endl
#define p3(a, b, c) idp cout << a << "\\t" << b << "\\t" << c << endl
#define p4(a, b, c, d)                                                         \\
  idp cout << a << "\\t" << b << "\\t" << c << "\\t" << d << endl
#define p5(a, b, c, d, e)                                                      \\
  idp cout << a << "\\t" << b << "\\t" << c << "\\t" << d << "\\t" << e << endl
#define p6(a, b, c, d, e, f)                                                   \\
  idp cout << a << "\\t" << b << "\\t" << c << "\\t" << d << "\\t" << e << "\\t"    \\
           << f << endl
#define p7(a, b, c, d, e, f, g)                                                \\
  idp cout << a << "\\t" << b << "\\t" << c << "\\t" << d << "\\t" << e << "\\t"    \\
           << f << "\\t" << g << endl
#define p8(a, b, c, d, e, f, g, h)                                             \\
  idp cout << a << "\\t" << b << "\\t" << c << "\\t" << d << "\\t" << e << "\\t"    \\
           << f << "\\t" << g << "\\t" << h << endl
#define p9(a, b, c, d, e, f, g, h, i)                                          \\
  idp cout << a << "\\t" << b << "\\t" << c << "\\t" << d << "\\t" << e << "\\t"    \\
           << f << "\\t" << g << "\\t" << h << "\\t" << i << endl
#define p10(a, b, c, d, e, f, g, h, i, j)                                      \\
  idp cout << a << "\\t" << b << "\\t" << c << "\\t" << d << "\\t" << e << "\\t"    \\
           << f << "\\t" << g << "\\t" << h << "\\t" << i << "\\t" << j << endl
#define foreach(it, v)                                                         \\
  for (__typeof((v).begin()) it = (v).begin(); it != (v).end(); ++it)
#define p2p(x) idp p2((x).F, (x).S)
#define dump(x, n)                                                             \\
  idp {                                                                        \\
    rep(i, n) { cout << x[i] << " "; }                                         \\
    puts("");                                                                  \\
  }
#define dump2(x, n)                                                            \\
  idp {                                                                        \\
    rep(i, n) { cout << "[" << x[i].F << " , " << x[i].S << "] "; }            \\
    puts("");                                                                  \\
  }
#define dumpi(x)                                                               \\
  idp {                                                                        \\
    foreach (it, x) {                                                          \\
      cout << (*it) << " ";                                                    \\
    }                                                                          \\
    puts("");                                                                  \\
  }
#define dumpi2(x)                                                              \\
  idp {                                                                        \\
    foreach (it, x) {                                                          \\
      cout << "[" << (it)->F << " , " << (it)->S << "] ";                      \\
    }                                                                          \\
    puts("");                                                                  \\
  }

#define read2d(a, w, h) rep(i, h) rep(j, w) cin >> a[i][j]
#define dump2d(a, w, h)                                                        \\
  rep(i, h) {                                                                  \\
    rep(j, w) cout << a[i][j] << " ";                                          \\
    puts("");                                                                  \\
  }

typedef pair<li, li> PI;

li fact_mod[200100];

inline void init() {
  fact_mod[0] = 1;
  fact_mod[1] = 1;
  repp(i, 2, 200100) { fact_mod[i] = (fact_mod[i - 1] * i) % MOD; }
}

inline li gcd(li a, li b) { return b != 0 ? gcd(b, a % b) : a; }
// a x + b y = gcd(a, b)
inline li extgcd(li a, li b, li &x, li &y) {
  li g = a;
  x = 1;
  y = 0;
  if (b != 0)
    g = extgcd(b, a % b, y, x), y -= (a / b) * x;
  return g;
}

inline li invMod(li a) {
  li x, y;
  if (extgcd(a, MOD, x, y) == 1)
    return (x + MOD) % MOD;
  else
    return 0; // unsolvable
}

inline li combi(li n, li k) {
  return (((fact_mod[n] * invMod(fact_mod[k])) % MOD) *
          invMod(fact_mod[n - k])) %
         MOD;
}

vector<li> edge[200100];

// {from, to} -> node_num, order_num
unordered_map<li, PI> m[200100];

inline PI calc(li from, li now) {
  li res = 1;
  li vnum = 1;
  li vvp = 1;
  for (auto &&next : edge[now]) {
    if (next == from) {
      continue;
    }
    if (m[next].count(now) == 0) {
      m[next][now] = calc(now, next);
    }
    PI tmp = m[next][now];
    res = (res * tmp.S) % MOD;
    vnum += tmp.F;
    vvp = (vvp * combi(vnum - 1, tmp.F)) % MOD;
  }

  res = (res * vvp) % MOD;
  if (from == -1) {
    for (auto &&next : edge[now]) {
      if (m[now].count(next) > 0) {
        continue;
      }
      // いっこダメだった場合を計算する
      PI tmp = m[next][now];
      li tres = res;
      tres = (tres * invMod(combi(vnum - 1, tmp.F))) % MOD;
      tres = (tres * invMod(m[next][now].S)) % MOD;
      m[now][next] = {vnum - tmp.F, tres};
    }
  }
  return {vnum, res};
}
int main() {
  init();
  li n;
  cin >> n;
  rep(i, n - 1) {
    li a, b;
    cin >> a >> b;
    a--;
    b--;
    edge[a].pb(b);
    edge[b].pb(a);
  }

  vector<PI> order;
  rin { order.pb({sz(edge[i]), i}); }
  sort(allof(order));
  reverse(allof(order));

  rin { cout << calc(-1, i).S << endl; }

  return 0;
}