Problem p02986 (C++)

Buggy submission (status: Runtime Error):
#pragma region
#include <bits/stdc++.h>
using namespace std;
/*
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
*/
#define int long long
#define REP(i, n) for (int i = 0; i < (int)(n); i++)
#define RREP(i, n) for (int i = (int)n - 1; i >= 0; i--)
#define FOR(i, s, n) for (int i = s; i < (int)n; i++)
#define RFOR(i, s, n) for (int i = (int)n - 1; i >= s; i--)
#define ALL(a) a.begin(), a.end()
#define IN(a, x, b) (a <= x && x < b)
template <class T> inline bool CHMAX(T &a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> inline bool CHMIN(T &a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> istream &operator>>(istream &is, vector<T> &vec) {
  for (T &x : vec)
    is >> x;
  return is;
}
template <class T> inline void in(T &t) { cin >> t; }
template <class T, class... Ts> inline void in(T &t, Ts &...ts) {
  cin >> t;
  in(ts...);
}
template <class T> inline void out(T t) { cout << t << "\n"; }
template <class T, class... Ts> inline void out(T t, Ts... ts) {
  cout << t << " ";
  out(ts...);
}
template <typename T = int> vector<T> mv(size_t a) { return vector<T>(a); }
template <typename T = int, typename... Ts> auto mv(size_t a, Ts... ts) {
  return vector<decltype(mv<T>(ts...))>(a, mv<T>(ts...));
}
template <typename T, typename V>
typename enable_if<is_class<T>::value == 0>::type fill(T &t, const V &v) {
  t = v;
}
template <typename T, typename V>
typename enable_if<is_class<T>::value != 0>::type fill(T &t, const V &v) {
  for (auto &e : t)
    fill(e, v);
}
constexpr long long INF = 1e18;

template <int MOD> struct Fp {
  long long val;
  constexpr Fp(long long v = 0) noexcept : val(v % MOD) {
    if (val < 0)
      val += MOD;
  }
  constexpr int getmod() { return MOD; }
  constexpr Fp operator-() const noexcept { return val ? MOD - val : 0; }
  constexpr Fp operator+(const Fp &r) const noexcept { return Fp(*this) += r; }
  constexpr Fp operator-(const Fp &r) const noexcept { return Fp(*this) -= r; }
  constexpr Fp operator*(const Fp &r) const noexcept { return Fp(*this) *= r; }
  constexpr Fp operator/(const Fp &r) const noexcept { return Fp(*this) /= r; }
  constexpr Fp &operator+=(const Fp &r) noexcept {
    val += r.val;
    if (val >= MOD)
      val -= MOD;
    return *this;
  }
  constexpr Fp &operator-=(const Fp &r) noexcept {
    val -= r.val;
    if (val < 0)
      val += MOD;
    return *this;
  }
  constexpr Fp &operator*=(const Fp &r) noexcept {
    val = val * r.val % MOD;
    return *this;
  }
  constexpr Fp &operator/=(const Fp &r) noexcept {
    long long a = r.val, b = MOD, u = 1, v = 0;
    while (b) {
      long long t = a / b;
      a -= t * b;
      swap(a, b);
      u -= t * v;
      swap(u, v);
    }
    val = val * u % MOD;
    if (val < 0)
      val += MOD;
    return *this;
  }
  constexpr bool operator==(const Fp &r) const noexcept {
    return this->val == r.val;
  }
  constexpr bool operator!=(const Fp &r) const noexcept {
    return this->val != r.val;
  }
  friend constexpr ostream &operator<<(ostream &os, const Fp<MOD> &x) noexcept {
    return os << x.val;
  }
  friend constexpr Fp<MOD> modpow(const Fp<MOD> &a, long long n) noexcept {
    if (n == 0)
      return 1;
    auto t = modpow(a, n / 2);
    t = t * t;
    if (n & 1)
      t = t * a;
    return t;
  }
};

// 二項係数ライブラリ
template <class T> struct BiCoef {
  vector<T> fact_, inv_, finv_;
  constexpr BiCoef() {}
  constexpr BiCoef(int n) noexcept : fact_(n, 1), inv_(n, 1), finv_(n, 1) {
    init(n);
  }
  constexpr void init(int n) noexcept {
    fact_.assign(n, 1), inv_.assign(n, 1), finv_.assign(n, 1);
    int MOD = fact_[0].getmod();
    for (int i = 2; i < n; i++) {
      fact_[i] = fact_[i - 1] * i;
      inv_[i] = -inv_[MOD % i] * (MOD / i);
      finv_[i] = finv_[i - 1] * inv_[i];
    }
  }
  constexpr T com(int n, int k) const noexcept {
    if (n < k || n < 0 || k < 0)
      return 0;
    return fact_[n] * finv_[k] * finv_[n - k];
  }
  constexpr T fact(int n) const noexcept {
    if (n < 0)
      return 0;
    return fact_[n];
  }
  constexpr T inv(int n) const noexcept {
    if (n < 0)
      return 0;
    return inv_[n];
  }
  constexpr T finv(int n) const noexcept {
    if (n < 0)
      return 0;
    return finv_[n];
  }
};

// const int MOD = 1000000007;
// const int MOD = 998244353;
// using mint = Fp<MOD>;
// BiCoef<mint> bc;
//  bc.init(500050);
#pragma endregion

template <typename T> struct edge {
  int src, to;
  T cost;

  edge(int to, T cost) : src(-1), to(to), cost(cost) {}

  edge(int src, int to, T cost) : src(src), to(to), cost(cost) {}

  edge &operator=(const int &x) {
    to = x;
    return *this;
  }

  operator int() const { return to; }
};
template <typename T> using Edges = vector<edge<T>>;
template <typename T> using WeightedGraph = vector<Edges<T>>;
using UnWeightedGraph = vector<vector<int>>;
template <typename T> using Matrix = vector<vector<T>>;
template <typename G> struct DoublingLowestCommonAncestor {
  const int LOG;
  vector<int> dep;
  const G &g;
  vector<vector<int>> table;

  DoublingLowestCommonAncestor(const G &g)
      : g(g), dep(g.size()), LOG(32 - __builtin_clz(g.size())) {
    table.assign(LOG, vector<int>(g.size(), -1));
  }

  void dfs(int idx, int par, int d) {
    table[0][idx] = par;
    dep[idx] = d;
    for (auto &to : g[idx]) {
      if (to != par)
        dfs(to, idx, d + 1);
    }
  }

  void build() {
    dfs(0, -1, 0); // ここを書き換えれば親を選択できる
    for (int k = 0; k + 1 < LOG; k++) {
      for (int i = 0; i < table[k].size(); i++) {
        if (table[k][i] == -1)
          table[k + 1][i] = -1;
        else
          table[k + 1][i] = table[k][table[k][i]];
      }
    }
  }

  int query(int u, int v) {
    if (dep[u] > dep[v])
      swap(u, v);
    for (int i = LOG - 1; i >= 0; i--) {
      if (((dep[v] - dep[u]) >> i) & 1)
        v = table[i][v];
    }
    if (u == v)
      return u;
    for (int i = LOG - 1; i >= 0; i--) {
      if (table[i][u] != table[i][v]) {
        u = table[i][u];
        v = table[i][v];
      }
    }
    return table[0][u];
  }
};

struct SegmentTree {
  int n;
  pair<int, int> ti = pair<int, int>(0, 0);
  vector<map<int, pair<int, int>>> dat;
  SegmentTree(){};
  void init(int n_) {
    n = 1;
    while (n < n_)
      n <<= 1;
    dat.resize(n << 1);
  }
  void build(int N) {
    int n_ = N;
    init(n_);
  }
  pair<int, int> f(pair<int, int> a, pair<int, int> b) {
    return {a.first + b.first, a.second + b.second};
  }
  void set_val(int k, pair<int, int> x, int col) {
    dat[k += n][col] = x;
    while (k >>= 1)
      dat[k][col] = f(dat[(k << 1) | 0][col], dat[(k << 1) | 1][col]);
  }
  pair<int, int> query(int a, int b, int col) {
    pair<int, int> vl = ti, vr = ti;
    for (int l = a + n, r = b + n; l < r; l >>= 1, r >>= 1) {
      if (l & 1)
        vl = f(vl, dat[l++][col]);
      if (r & 1)
        vr = f(dat[--r][col], vr);
    }
    return f(vl, vr);
  }
};
// auto f = [](){};
// auto seg = SegmentTree<T,decltype(f)>(f,Ti);

signed main() {
  int N, Q;
  in(N, Q);
  WeightedGraph<int> g(N);
  auto c = mv(N - 1), d = c;
  REP(i, N - 1) {
    int a, b;
    in(a, b, c[i], d[i]);
    --a;
    --b;
    --c[i];
    g[a].emplace_back(b, i);
    g[b].emplace_back(a, i);
  }
  DoublingLowestCommonAncestor<WeightedGraph<int>> lca(g);
  lca.build();
  auto ds = mv(N), us = ds;
  fill(ds, -1);
  fill(us, -1);
  SegmentTree seg;
  seg.build(N);
  int idx = 0;
  vector<int> sum;
  sum.push_back(0);
  auto dfs = [&](auto &&f, int now, int par) -> void {
    for (auto e : g[now]) {
      if (e == par)
        continue;
      ds[e] = idx;
      seg.set_val(idx, {d[e.cost], 1}, c[e.cost]);
      sum.push_back(d[e.cost]);
      ++idx;
      f(f, e, now);
      us[e] = idx;
      seg.set_val(idx, {-d[e.cost], -1}, c[e.cost]);
      sum.push_back(-d[e.cost]);
      ++idx;
    }
  };
  dfs(dfs, 0, -1);
  REP(i, sum.size() - 1) sum[i + 1] += sum[i];
  vector<int> ans;
  while (Q--) {
    int x, y, a, b;
    in(x, y, a, b);
    x--;
    a--;
    b--;
    int p = lca.query(a, b);
    int ret = 0;
    auto f = [&](int child) {
      int l = ds[p] + 1, r = ds[child] + 1;
      int res = sum[r] - sum[l];
      auto p = seg.query(l, r, x);
      res -= p.first;
      res += p.second * y;
      return res;
    };
    ret += f(a);
    ret += f(b);
    ans.push_back(ret);
  }
  REP(i, ans.size()) { out(ans[i]); }
}

Fixed submission:
#pragma region
#include <bits/stdc++.h>
using namespace std;
/*
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
*/
#define int long long
#define REP(i, n) for (int i = 0; i < (int)(n); i++)
#define RREP(i, n) for (int i = (int)n - 1; i >= 0; i--)
#define FOR(i, s, n) for (int i = s; i < (int)n; i++)
#define RFOR(i, s, n) for (int i = (int)n - 1; i >= s; i--)
#define ALL(a) a.begin(), a.end()
#define IN(a, x, b) (a <= x && x < b)
template <class T> inline bool CHMAX(T &a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> inline bool CHMIN(T &a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> istream &operator>>(istream &is, vector<T> &vec) {
  for (T &x : vec)
    is >> x;
  return is;
}
template <class T> inline void in(T &t) { cin >> t; }
template <class T, class... Ts> inline void in(T &t, Ts &...ts) {
  cin >> t;
  in(ts...);
}
template <class T> inline void out(T t) { cout << t << "\n"; }
template <class T, class... Ts> inline void out(T t, Ts... ts) {
  cout << t << " ";
  out(ts...);
}
template <typename T = int> vector<T> mv(size_t a) { return vector<T>(a); }
template <typename T = int, typename... Ts> auto mv(size_t a, Ts... ts) {
  return vector<decltype(mv<T>(ts...))>(a, mv<T>(ts...));
}
template <typename T, typename V>
typename enable_if<is_class<T>::value == 0>::type fill(T &t, const V &v) {
  t = v;
}
template <typename T, typename V>
typename enable_if<is_class<T>::value != 0>::type fill(T &t, const V &v) {
  for (auto &e : t)
    fill(e, v);
}
constexpr long long INF = 1e18;

template <int MOD> struct Fp {
  long long val;
  constexpr Fp(long long v = 0) noexcept : val(v % MOD) {
    if (val < 0)
      val += MOD;
  }
  constexpr int getmod() { return MOD; }
  constexpr Fp operator-() const noexcept { return val ? MOD - val : 0; }
  constexpr Fp operator+(const Fp &r) const noexcept { return Fp(*this) += r; }
  constexpr Fp operator-(const Fp &r) const noexcept { return Fp(*this) -= r; }
  constexpr Fp operator*(const Fp &r) const noexcept { return Fp(*this) *= r; }
  constexpr Fp operator/(const Fp &r) const noexcept { return Fp(*this) /= r; }
  constexpr Fp &operator+=(const Fp &r) noexcept {
    val += r.val;
    if (val >= MOD)
      val -= MOD;
    return *this;
  }
  constexpr Fp &operator-=(const Fp &r) noexcept {
    val -= r.val;
    if (val < 0)
      val += MOD;
    return *this;
  }
  constexpr Fp &operator*=(const Fp &r) noexcept {
    val = val * r.val % MOD;
    return *this;
  }
  constexpr Fp &operator/=(const Fp &r) noexcept {
    long long a = r.val, b = MOD, u = 1, v = 0;
    while (b) {
      long long t = a / b;
      a -= t * b;
      swap(a, b);
      u -= t * v;
      swap(u, v);
    }
    val = val * u % MOD;
    if (val < 0)
      val += MOD;
    return *this;
  }
  constexpr bool operator==(const Fp &r) const noexcept {
    return this->val == r.val;
  }
  constexpr bool operator!=(const Fp &r) const noexcept {
    return this->val != r.val;
  }
  friend constexpr ostream &operator<<(ostream &os, const Fp<MOD> &x) noexcept {
    return os << x.val;
  }
  friend constexpr Fp<MOD> modpow(const Fp<MOD> &a, long long n) noexcept {
    if (n == 0)
      return 1;
    auto t = modpow(a, n / 2);
    t = t * t;
    if (n & 1)
      t = t * a;
    return t;
  }
};

// 二項係数ライブラリ
template <class T> struct BiCoef {
  vector<T> fact_, inv_, finv_;
  constexpr BiCoef() {}
  constexpr BiCoef(int n) noexcept : fact_(n, 1), inv_(n, 1), finv_(n, 1) {
    init(n);
  }
  constexpr void init(int n) noexcept {
    fact_.assign(n, 1), inv_.assign(n, 1), finv_.assign(n, 1);
    int MOD = fact_[0].getmod();
    for (int i = 2; i < n; i++) {
      fact_[i] = fact_[i - 1] * i;
      inv_[i] = -inv_[MOD % i] * (MOD / i);
      finv_[i] = finv_[i - 1] * inv_[i];
    }
  }
  constexpr T com(int n, int k) const noexcept {
    if (n < k || n < 0 || k < 0)
      return 0;
    return fact_[n] * finv_[k] * finv_[n - k];
  }
  constexpr T fact(int n) const noexcept {
    if (n < 0)
      return 0;
    return fact_[n];
  }
  constexpr T inv(int n) const noexcept {
    if (n < 0)
      return 0;
    return inv_[n];
  }
  constexpr T finv(int n) const noexcept {
    if (n < 0)
      return 0;
    return finv_[n];
  }
};

// const int MOD = 1000000007;
// const int MOD = 998244353;
// using mint = Fp<MOD>;
// BiCoef<mint> bc;
//  bc.init(500050);
#pragma endregion

template <typename T> struct edge {
  int src, to;
  T cost;

  edge(int to, T cost) : src(-1), to(to), cost(cost) {}

  edge(int src, int to, T cost) : src(src), to(to), cost(cost) {}

  edge &operator=(const int &x) {
    to = x;
    return *this;
  }

  operator int() const { return to; }
};
template <typename T> using Edges = vector<edge<T>>;
template <typename T> using WeightedGraph = vector<Edges<T>>;
using UnWeightedGraph = vector<vector<int>>;
template <typename T> using Matrix = vector<vector<T>>;
template <typename G> struct DoublingLowestCommonAncestor {
  const int LOG;
  vector<int> dep;
  const G &g;
  vector<vector<int>> table;

  DoublingLowestCommonAncestor(const G &g)
      : g(g), dep(g.size()), LOG(32 - __builtin_clz(g.size())) {
    table.assign(LOG, vector<int>(g.size(), -1));
  }

  void dfs(int idx, int par, int d) {
    table[0][idx] = par;
    dep[idx] = d;
    for (auto &to : g[idx]) {
      if (to != par)
        dfs(to, idx, d + 1);
    }
  }

  void build() {
    dfs(0, -1, 0); // ここを書き換えれば親を選択できる
    for (int k = 0; k + 1 < LOG; k++) {
      for (int i = 0; i < table[k].size(); i++) {
        if (table[k][i] == -1)
          table[k + 1][i] = -1;
        else
          table[k + 1][i] = table[k][table[k][i]];
      }
    }
  }

  int query(int u, int v) {
    if (dep[u] > dep[v])
      swap(u, v);
    for (int i = LOG - 1; i >= 0; i--) {
      if (((dep[v] - dep[u]) >> i) & 1)
        v = table[i][v];
    }
    if (u == v)
      return u;
    for (int i = LOG - 1; i >= 0; i--) {
      if (table[i][u] != table[i][v]) {
        u = table[i][u];
        v = table[i][v];
      }
    }
    return table[0][u];
  }
};

struct SegmentTree {
  int n;
  pair<int, int> ti = pair<int, int>(0, 0);
  vector<map<int, pair<int, int>>> dat;
  SegmentTree(){};
  void init(int n_) {
    n = 1;
    while (n < n_)
      n <<= 1;
    dat.resize(n << 1);
  }
  void build(int N) {
    int n_ = N;
    init(n_);
  }
  pair<int, int> f(pair<int, int> a, pair<int, int> b) {
    return {a.first + b.first, a.second + b.second};
  }
  void set_val(int k, pair<int, int> x, int col) {
    dat[k += n][col] = x;
    while (k >>= 1)
      dat[k][col] = f(dat[(k << 1) | 0][col], dat[(k << 1) | 1][col]);
  }
  pair<int, int> query(int a, int b, int col) {
    pair<int, int> vl = ti, vr = ti;
    for (int l = a + n, r = b + n; l < r; l >>= 1, r >>= 1) {
      if (l & 1)
        vl = f(vl, dat[l++][col]);
      if (r & 1)
        vr = f(dat[--r][col], vr);
    }
    return f(vl, vr);
  }
};
// auto f = [](){};
// auto seg = SegmentTree<T,decltype(f)>(f,Ti);

signed main() {
  int N, Q;
  in(N, Q);
  WeightedGraph<int> g(N);
  auto c = mv(N - 1), d = c;
  REP(i, N - 1) {
    int a, b;
    in(a, b, c[i], d[i]);
    --a;
    --b;
    --c[i];
    g[a].emplace_back(b, i);
    g[b].emplace_back(a, i);
  }
  DoublingLowestCommonAncestor<WeightedGraph<int>> lca(g);
  lca.build();
  auto ds = mv(N), us = ds;
  fill(ds, -1);
  fill(us, -1);
  SegmentTree seg;
  seg.build(2 * N);
  int idx = 0;
  vector<int> sum;
  sum.push_back(0);
  auto dfs = [&](auto &&f, int now, int par) -> void {
    for (auto e : g[now]) {
      if (e == par)
        continue;
      ds[e] = idx;
      seg.set_val(idx, {d[e.cost], 1}, c[e.cost]);
      sum.push_back(d[e.cost]);
      ++idx;
      f(f, e, now);
      us[e] = idx;
      seg.set_val(idx, {-d[e.cost], -1}, c[e.cost]);
      sum.push_back(-d[e.cost]);
      ++idx;
    }
  };
  dfs(dfs, 0, -1);
  REP(i, sum.size() - 1) sum[i + 1] += sum[i];
  vector<int> ans;
  while (Q--) {
    int x, y, a, b;
    in(x, y, a, b);
    x--;
    a--;
    b--;
    int p = lca.query(a, b);
    int ret = 0;
    auto f = [&](int child) {
      int l = ds[p] + 1, r = ds[child] + 1;
      int res = sum[r] - sum[l];
      auto p = seg.query(l, r, x);
      res -= p.first;
      res += p.second * y;
      return res;
    };
    ret += f(a);
    ret += f(b);
    ans.push_back(ret);
  }
  REP(i, ans.size()) { out(ans[i]); }
}