結果

問題 No.1333 Squared Sum
ユーザー 👑 emthrmemthrm
提出日時 2021-02-07 01:47:03
言語 C++17
(gcc 12.3.0 + boost 1.83.0)
結果
AC  
実行時間 198 ms / 2,000 ms
コード長 6,132 bytes
コンパイル時間 2,397 ms
コンパイル使用メモリ 210,692 KB
実行使用メモリ 41,472 KB
最終ジャッジ日時 2024-07-03 13:38:48
合計ジャッジ時間 10,116 ms
ジャッジサーバーID
（参考情報） 		judge1 / judge3
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テストケース

テストケース表示
入力 結果 実行時間
実行使用メモリ
testcase_00 AC 2 ms
5,248 KB
testcase_01 AC 1 ms
5,376 KB
testcase_02 AC 2 ms
5,376 KB
testcase_03 AC 168 ms
18,560 KB
testcase_04 AC 166 ms
18,360 KB
testcase_05 AC 184 ms
18,432 KB
testcase_06 AC 163 ms
18,560 KB
testcase_07 AC 174 ms
18,576 KB
testcase_08 AC 165 ms
18,528 KB
testcase_09 AC 175 ms
18,560 KB
testcase_10 AC 163 ms
18,468 KB
testcase_11 AC 164 ms
18,560 KB
testcase_12 AC 185 ms
18,468 KB
testcase_13 AC 151 ms
41,472 KB
testcase_14 AC 189 ms
29,136 KB
testcase_15 AC 193 ms
38,324 KB
testcase_16 AC 2 ms
5,376 KB
testcase_17 AC 1 ms
5,376 KB
testcase_18 AC 1 ms
5,376 KB
testcase_19 AC 2 ms
5,376 KB
testcase_20 AC 2 ms
5,376 KB
testcase_21 AC 2 ms
5,376 KB
testcase_22 AC 2 ms
5,376 KB
testcase_23 AC 1 ms
5,376 KB
testcase_24 AC 2 ms
5,376 KB
testcase_25 AC 1 ms
5,376 KB
testcase_26 AC 189 ms
40,704 KB
testcase_27 AC 198 ms
29,824 KB
testcase_28 AC 182 ms
40,536 KB
testcase_29 AC 151 ms
41,472 KB
testcase_30 AC 54 ms
9,600 KB
testcase_31 AC 30 ms
6,784 KB
testcase_32 AC 85 ms
12,416 KB
testcase_33 AC 60 ms
10,624 KB
testcase_34 AC 112 ms
15,360 KB
testcase_35 AC 86 ms
12,416 KB
testcase_36 AC 45 ms
8,832 KB
testcase_37 AC 50 ms
8,960 KB
testcase_38 AC 55 ms
9,984 KB
testcase_39 AC 98 ms
13,824 KB
testcase_40 AC 127 ms
18,744 KB
testcase_41 AC 133 ms
18,872 KB
testcase_42 AC 119 ms
18,876 KB
testcase_43 AC 109 ms
19,004 KB
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ソースコード

diff # 

#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
using namespace std;
#define FOR(i,m,n) for(int i=(m);i<(n);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()
using ll = long long;
constexpr int INF = 0x3f3f3f3f;
constexpr long long LINF = 0x3f3f3f3f3f3f3f3fLL;
constexpr double EPS = 1e-8;
constexpr int MOD = 1000000007;
// constexpr int MOD = 998244353;
constexpr int dy[] = {1, 0, -1, 0}, dx[] = {0, -1, 0, 1};
constexpr int dy8[] = {1, 1, 0, -1, -1, -1, 0, 1}, dx8[] = {0, -1, -1, -1, 0, 1, 1, 1};
template <typename T, typename U> inline bool chmax(T &a, U b) { return a < b ? (a = b, true) : false; }
template <typename T, typename U> inline bool chmin(T &a, U b) { return a > b ? (a = b, true) : false; }
struct IOSetup {
  IOSetup() {
    std::cin.tie(nullptr);
    std::ios_base::sync_with_stdio(false);
    std::cout << fixed << setprecision(20);
  }
} iosetup;

template <int MOD>
struct MInt {
  unsigned val;
  MInt(): val(0) {}
  MInt(long long x) : val(x >= 0 ? x % MOD : x % MOD + MOD) {}
  static int get_mod() { return MOD; }
  static void set_mod(int divisor) { assert(divisor == MOD); }
  MInt pow(long long exponent) const {
    MInt tmp = *this, res = 1;
    while (exponent > 0) {
      if (exponent & 1) res *= tmp;
      tmp *= tmp;
      exponent >>= 1;
    }
    return res;
  }
  MInt &operator+=(const MInt &x) { if((val += x.val) >= MOD) val -= MOD; return *this; }
  MInt &operator-=(const MInt &x) { if((val += MOD - x.val) >= MOD) val -= MOD; return *this; }
  MInt &operator*=(const MInt &x) { val = static_cast<unsigned long long>(val) * x.val % MOD; return *this; }
  MInt &operator/=(const MInt &x) {
    // assert(std::__gcd(static_cast<int>(x.val), MOD) == 1);
    unsigned a = x.val, b = MOD; int u = 1, v = 0;
    while (b) {
      unsigned tmp = a / b;
      std::swap(a -= tmp * b, b);
      std::swap(u -= tmp * v, v);
    }
    return *this *= u;
  }
  bool operator==(const MInt &x) const { return val == x.val; }
  bool operator!=(const MInt &x) const { return val != x.val; }
  bool operator<(const MInt &x) const { return val < x.val; }
  bool operator<=(const MInt &x) const { return val <= x.val; }
  bool operator>(const MInt &x) const { return val > x.val; }
  bool operator>=(const MInt &x) const { return val >= x.val; }
  MInt &operator++() { if (++val == MOD) val = 0; return *this; }
  MInt operator++(int) { MInt res = *this; ++*this; return res; }
  MInt &operator--() { val = (val == 0 ? MOD : val) - 1; return *this; }
  MInt operator--(int) { MInt res = *this; --*this; return res; }
  MInt operator+() const { return *this; }
  MInt operator-() const { return MInt(val ? MOD - val : 0); }
  MInt operator+(const MInt &x) const { return MInt(*this) += x; }
  MInt operator-(const MInt &x) const { return MInt(*this) -= x; }
  MInt operator*(const MInt &x) const { return MInt(*this) *= x; }
  MInt operator/(const MInt &x) const { return MInt(*this) /= x; }
  friend std::ostream &operator<<(std::ostream &os, const MInt &x) { return os << x.val; }
  friend std::istream &operator>>(std::istream &is, MInt &x) { long long val; is >> val; x = MInt(val); return is; }
};
namespace std { template <int MOD> MInt<MOD> abs(const MInt<MOD> &x) { return x; } }
template <int MOD>
struct Combinatorics {
  using ModInt = MInt<MOD>;
  int val;  // "val!" and "mod" must be disjoint.
  std::vector<ModInt> fact, fact_inv, inv;
  Combinatorics(int val = 10000000) : val(val), fact(val + 1), fact_inv(val + 1), inv(val + 1) {
    fact[0] = 1;
    for (int i = 1; i <= val; ++i) fact[i] = fact[i - 1] * i;
    fact_inv[val] = ModInt(1) / fact[val];
    for (int i = val; i > 0; --i) fact_inv[i - 1] = fact_inv[i] * i;
    for (int i = 1; i <= val; ++i) inv[i] = fact[i - 1] * fact_inv[i];
  }
  ModInt nCk(int n, int k) const {
    if (n < 0 || n < k || k < 0) return 0;
    assert(n <= val && k <= val);
    return fact[n] * fact_inv[k] * fact_inv[n - k];
  }
  ModInt nPk(int n, int k) const {
    if (n < 0 || n < k || k < 0) return 0;
    assert(n <= val);
    return fact[n] * fact_inv[n - k];
  }
  ModInt nHk(int n, int k) const {
    if (n < 0 || k < 0) return 0;
    return k == 0 ? 1 : nCk(n + k - 1, k);
  }
};
using ModInt = MInt<MOD>;

template <typename CostType>
struct Edge {
  int src, dst; CostType cost;
  Edge(int src, int dst, CostType cost = 0) : src(src), dst(dst), cost(cost) {}
  inline bool operator<(const Edge &x) const {
    return cost != x.cost ? cost < x.cost : dst != x.dst ? dst < x.dst : src < x.src;
  }
  inline bool operator<=(const Edge &x) const { return !(x < *this); }
  inline bool operator>(const Edge &x) const { return x < *this; }
  inline bool operator>=(const Edge &x) const { return !(*this < x); }
};

int main() {
  int n; cin >> n;
  vector<vector<Edge<int>>> graph(n);
  REP(_, n - 1) {
    int u, v, w; cin >> u >> v >> w; --u; --v;
    graph[u].emplace_back(u, v, w);
    graph[v].emplace_back(v, u, w);
  }
  vector<ModInt> squared_sum(n, 0), sum(n, 0);
  vector<int> subtree(n, 1);
  auto f = [&](auto &&f, int par, int ver) -> void {
    for (const Edge<int> &e : graph[ver]) {
      if (e.dst != par) {
        f(f, ver, e.dst);
        squared_sum[ver] += squared_sum[e.dst] + sum[e.dst] * e.cost * 2 + ModInt(e.cost) * e.cost * subtree[e.dst];
        sum[ver] += sum[e.dst] + ModInt(e.cost) * subtree[e.dst];
        subtree[ver] += subtree[e.dst];
      }
    }
  };
  f(f, -1, 0);
  ModInt ans = 0;
  auto g = [&](auto &&g, int par, int ver, ModInt ss, ModInt s) -> void {
    squared_sum[ver] += ss;
    sum[ver] += s;
    ans += squared_sum[ver];
    for (const Edge<int> &e : graph[ver]) {
      if (e.dst != par) {
        ModInt nx_ss = squared_sum[ver], nx_s = sum[ver];
        nx_ss -= squared_sum[e.dst] + sum[e.dst] * e.cost * 2 + ModInt(e.cost) * e.cost * subtree[e.dst];
        nx_s -= sum[e.dst] + ModInt(e.cost) * subtree[e.dst];
        g(g, ver, e.dst,
          nx_ss + nx_s * e.cost * 2 + ModInt(e.cost) * e.cost * (n - subtree[e.dst]),
          nx_s + ModInt(e.cost) * (n - subtree[e.dst]));
      }
    }
  };
  g(g, -1, 0, 0, 0);
  cout << ans / 2 << '\n';
  return 0;
}
0