結果
| 問題 | No.1333 Squared Sum |
| ユーザー |
👑  emthrm
|
| 提出日時 | 2021-02-07 01:47:03 |
| 言語 | C++17 (gcc 13.3.0 + boost 1.87.0) |
| 結果 |
AC
|
| 実行時間 | 184 ms / 2,000 ms |
| コード長 | 6,132 bytes |
| コンパイル時間 | 2,000 ms |
| コンパイル使用メモリ | 205,116 KB |
| 最終ジャッジ日時 | 2025-01-18 13:45:11 |
|
ジャッジサーバーID （参考情報） |
judge5 / judge3 |
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| ファイルパターン | 結果 |
|---|---|
| other | AC * 44 |
ソースコード
#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;}