結果
問題 | No.1333 Squared Sum |
ユーザー |
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提出日時 | 2021-01-08 23:19:06 |
言語 | C++17 (gcc 13.3.0 + boost 1.87.0) |
結果 |
AC
|
実行時間 | 237 ms / 2,000 ms |
コード長 | 3,411 bytes |
コンパイル時間 | 1,151 ms |
コンパイル使用メモリ | 94,836 KB |
最終ジャッジ日時 | 2025-01-17 14:34:05 |
ジャッジサーバーID (参考情報) |
judge4 / judge2 |
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ファイルパターン | 結果 |
---|---|
other | AC * 44 |
ソースコード
#include <iostream>#include <algorithm>#include <iomanip>#include <vector>#include <queue>#include <set>#include <map>#include <cassert>#define debug_value(x) cerr << "line" << __LINE__ << ":<" << __func__ << ">:" << #x << "=" << x << endl;#define debug(x) cerr << "line" << __LINE__ << ":<" << __func__ << ">:" << x << endl;template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }using namespace std;typedef long long ll;const ll MOD = 1000000007;class ModInt{public:ll v;ModInt(ll _v = 0){if(_v >= MOD) _v %= MOD;v = _v;}ModInt operator+(ll n){return ModInt((v+n)%MOD);}ModInt operator-(ll n){return ModInt((v-n+MOD)%MOD);}ModInt operator*(ll n){if(n >= MOD) n %= MOD;return ModInt((v*n)%MOD);}ModInt operator/(ll n){return ModInt((ModInt(n).inv()*v).v%MOD);}void operator+=(ll n){v = (v+n)%MOD;}void operator-=(ll n){v = (v-n+MOD)%MOD;}void operator*=(ll n){v = (v*n)%MOD;}ModInt operator+(ModInt n){return ModInt((v+n.v)%MOD);}ModInt operator-(ModInt n){return ModInt((v-n.v+MOD)%MOD);}ModInt operator*(ModInt n){return ModInt((v*n.v)%MOD);}ModInt operator/(ModInt n){return ModInt((n.inv()*v).v%MOD);}void operator+=(ModInt n){v = (v+n.v)%MOD;}void operator-=(ModInt n){v = (v-n.v+MOD)%MOD;}void operator*=(ModInt n){v = (v*n.v)%MOD;}void operator=(ModInt n){v = n.v;}void operator=(ll n){v = n;}ModInt inv(){if(v == 1) return ModInt(1);else return ModInt(MOD-ModInt(MOD%v).inv().v*(MOD/v)%MOD);}};ostream& operator<<(ostream& os, const ModInt& m){os << m.v;return os;}istream & operator >> (istream &in, ModInt &m){in >> m.v;return in;}ModInt dp_sum[200000];ModInt dp_square[200000];ModInt cnt_ch[200000];struct edge{int to;ModInt cost;};int n;vector<edge> G[200000];ModInt ans;bool used[200000];void dfs(int v){used[v] = true;vector<edge> visited;for(auto e : G[v]){if(!used[e.to]){visited.push_back(e);dfs(e.to);cnt_ch[v] += cnt_ch[e.to];dp_square[v] += dp_square[e.to]+dp_sum[e.to]*e.cost*2+e.cost*e.cost*cnt_ch[e.to];dp_sum[v] += dp_sum[e.to]+e.cost*cnt_ch[e.to];}}for(edge e : visited){ModInt x = dp_square[e.to]+dp_sum[e.to]*e.cost*2+e.cost*e.cost*cnt_ch[e.to];ans += x*(cnt_ch[v]-cnt_ch[e.to]);x = dp_sum[e.to]+e.cost*cnt_ch[e.to];ans += x*(dp_sum[v]-x);}ans += dp_square[v];cnt_ch[v]+=1;// cout << v << ' ' << dp_sum[v] << ' ' << dp_square[v] << ' ' << ans << ' ' << cnt_ch[v] << endl;}int main(){ios::sync_with_stdio(false);cin.tie(0);cout << setprecision(10) << fixed;cin >> n;for(int i = 0; i < n-1; i++){int u, v;ModInt w;cin >> u >> v >> w;u--; v--;G[u].push_back((edge){v, w});G[v].push_back((edge){u, w});}dfs(0);cout << ans << endl;}