結果

問題 No.3113 The farthest point
ユーザー Katu2ou
提出日時 2025-04-19 11:12:03
言語 C++23
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 130 ms / 2,000 ms
コード長 9,156 bytes
コンパイル時間 6,638 ms
コンパイル使用メモリ 334,048 KB
実行使用メモリ 19,836 KB
最終ジャッジ日時 2025-04-19 11:12:13
合計ジャッジ時間 9,843 ms
ジャッジサーバーID
（参考情報） 		judge1 / judge5
このコードへのチャレンジ
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ファイルパターン 結果
sample AC * 3
other AC * 33
権限があれば一括ダウンロードができます

ソースコード

diff # 

//#pragma GCC optimize("O3")
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;

#define rep2(i, m, n) for (int i = (m); i < (n); ++i)
#define rep(i, n) rep2(i, 0, n)
#define drep2(i, m, n) for (int i = (m)-1; i >= (n); --i)
#define drep(i, n) drep2(i, n, 0)
#define all(...) std::begin(__VA_ARGS__), std::end(__VA_ARGS__)
#define rall(...) std::rbegin(__VA_ARGS__), std::rend(__VA_ARGS__)
#define CLR(a, b) memset((a), (b), sizeof(a))
#define DUMP(x) cout << #x << " = " << (x) << endl;
#define INF (long long)1001001001001001001
#define inf 1001001000
#define MOD 998244353
#define MOD1 1000000007
#define PI 3.14159265358979
#define epsilon 1e-12
#define fcout cout << fixed << setprecision(12)
#define MP make_pair
#define PB push_back
#define fi first
#define se second
#define ERASE(x) x.erase(unique(x.begin(),x.end()),x.end())

using ll = long long;
using ld = long double;
using vi = vector<int>;
using vl = vector<long long>;
using vs = vector<string>;
using vd = vector<double>;
using vld = vector<long double>;
using vb = vector<bool>;
using vpii = vector<pair<int, int>>;
using vpll = vector<pair<long long, long long>>;
using vvi = vector<vector<int>>;
using vvl = vector<vector<long long>>;
using vvd = vector<vector<double>>;
using vvld = vector<vector<long double>>;
using vvb = vector<vector<bool>>;
using vvpii = vector<vector<pair<int,int>>>;
using vvpll = vector<vector<pair<long long,long long>>>;
using vvvi = vector<vector<vector<int>>>;
using vvvl = vector<vector<vector<long long>>>;
using pii = pair<int, int>;
using pll = pair<long long, long long>;
using LL = __int128_t;
using mint = atcoder::modint998244353;
using vmint = vector<mint>;
using vvmint = vector<vector<mint>>;
using vvvmint = vector<vector<vector<mint>>>;

ll gcd(ll x, ll y) {if (x == 0) return y;	return gcd(y%x, x);} 
ll lcm(ll x, ll y) { __int128_t xx,yy; xx=x; yy=y; __int128_t ans=xx * yy / gcd(x, y); ll ans2=ans; return ans2; }
template<typename T>
T POW(T x, ll n){T ret=1;	while(n>0){		if(n&1) ret=ret*x;		x=x*x;		n>>=1;	}	return ret;}
template<typename T>
T modpow(T a, ll n, T p) {	if(n==0) return (T)1;  if (n == 1) return a % p;  if (n % 2 == 1) return (a * modpow(a, n - 1, p)) % p;  T t = modpow(a, n / 2, p);  return (t * t) % p;}
template<typename T>
T modinv(T a, T m) {	if(m==0)return (T)1;	T b = m, u = 1, v = 0;	while (b) {		T t = a / b;		a -= t * b; swap(a, b);		u -= t * v; swap(u, v);	}	u %= m;	if (u < 0) u += m;	return u;}
ll REM(ll a, ll b){ return (a % b + b) % b;}
ll QUO(ll a, ll b){ return (a - REM(a, b)) / b;}
/*
random_device rd;
mt19937 gen(rd());
uniform_int_distribution<> dist1(1, 100); [1,100]
int random_value = dist1(gen);
*/
/*
auto start = chrono::steady_clock::now(); //時間計測の開始
auto now = std::chrono::steady_clock::now(); //現在時刻と開始時刻の差を測定
double elapsed = std::chrono::duration<double>(now - start).count(); //時間をdouble型で取得
*/
/*
const int MAXCOMB=510000;
std::vector<mint> FAC(MAXCOMB), FINV(MAXCOMB), INV(MAXCOMB);
void COMinit() {FAC[0] = FAC[1] = 1;FINV[0] = FINV[1] = 1;INV[1] = 1;for (int i = 2; i < MAXCOMB; i++) {FAC[i] = FAC[i - 1] * i;INV[i] = mint(0) - INV[mint::mod() % i] * (mint::mod() / i);FINV[i] = FINV[i - 1] * INV[i];}}
mint COM(int n, int k) {if (n < k) return 0;if (n < 0 || k < 0) return 0;return FAC[n] * FINV[k] * FINV[n - k];}
*/

template <typename T> inline bool chmax(T &a, T b) { return ((a < b) ? (a = b, true) : (false));}
template <typename T> inline bool chmin(T &a, T b) { return ((a > b) ? (a = b, true) : (false));}
template <class T> T BS(vector<T> &vec, T key) {return lower_bound(vec.begin(), vec.end(), key) - vec.begin();}
template<class T> pair<T,T> RangeBS(vector<T> &vec, T lowv, T highv){auto itr_l = lower_bound(vec.begin(), vec.end(), lowv); auto itr_r = upper_bound(vec.begin(), vec.end(), highv); return make_pair(distance(vec.begin(), itr_l), distance(vec.begin(), itr_r)-1);}
void fail() { cout << "-1\n"; exit(0); } void no() { cout << "No\n"; exit(0); } void yes() { cout << "Yes\n"; exit(0); }
int dx[] = { 1,0,-1,0,1,1,-1,-1 }; int dy[] = { 0,1,0,-1,1,-1,1,-1};
bool range_in(int i, int j, int h, int w){ if(i<0 || j<0 || i>=h || j>=w) return false; return true;} 
int bitcount(int n){n=(n&0x55555555)+(n>>1&0x55555555); n=(n&0x33333333)+(n>>2&0x33333333); n=(n&0x0f0f0f0f)+(n>>4&0x0f0f0f0f); n=(n&0x00ff00ff)+(n>>8&0x00ff00ff); n=(n&0x0000ffff)+(n>>16&0x0000ffff); return n;}

template<typename T>
struct Edge{
    int from, to, index;
    T cost;
    Edge() : from(-1), to(-1), index(-1), cost(0) {}
    Edge(int _to) : from(-1), to(_to), index(-1), cost(0) {}
    Edge(int _to, T _cost) : from(-1), to(_to), index(-1), cost(_cost) {}
    Edge(int _from, int _to, int _index) : from(_from), to(_to), index(_index), cost(0) {}
    Edge(int _from, int _to, int _index, T _cost) 
        : from(_from), to(_to), index(_index), cost(_cost) {}
    bool operator<(const Edge<T>& other) const {
        return cost < other.cost; 
    }
    Edge &operator=(const int &x) {
        to = x;
        return *this;
    }
    operator int() const { return to; }
};
using Graph = vector<vector<int>>; 
template <typename T>
using WGraph = vector<vector<Edge<T>>>; 

/////////////////////////////////////////////////////////////////////////////////////////

template <class E, class V, E (*merge)(E, E), E (*e)(), E (*put_edge)(V, int), V (*put_vertex)(E, int)>
struct RerootingDP {
    struct edge {
        int to, idx, xdi;
    };
    RerootingDP(int n_ = 0) : n(n_), inner_edge_id(0) {
        es.resize(2*n-2);
        start.resize(2*n-2);
        if (n == 1) es_build();
    }
    void add_edge(int u, int v, int idx, int xdi){
        start[inner_edge_id] = u;
        es[inner_edge_id] = {v,idx,xdi};
        inner_edge_id++;
        start[inner_edge_id] = v;
        es[inner_edge_id] = {u,xdi,idx};
        inner_edge_id++;
        if (inner_edge_id == 2*n-2){
            es_build();
        }
    }
    vector<V> build(int root_ = 0){
        root = root_;
        vector<V> subdp(n); subdp[0] = put_vertex(e(),0);
        outs.resize(n);
        vector<int> geta(n+1,0);
        for (int i = 0; i < n; i++) geta[i+1] = start[i+1] - start[i] - 1;
        geta[root+1]++;
        for (int i = 0; i < n; i++) geta[i+1] += geta[i];
        auto dfs = [&](auto sfs, int v, int f) -> void {
            E val = e();
            for (int i = start[v]; i < start[v+1]; i++){
                if (es[i].to == f){
                    swap(es[start[v+1]-1],es[i]);
                }
                if (es[i].to == f) continue;
                sfs(sfs,es[i].to,v);
                E nval = put_edge(subdp[es[i].to],es[i].idx);
                outs[geta[v]++] = nval;
                val = merge(val,nval);
            }
            subdp[v] = put_vertex(val, v);
        };
        dfs(dfs,root,-1);
        return subdp;
    }
    vector<V> reroot(){
        vector<E> reverse_edge(n);
        reverse_edge[root] = e();
        vector<V> answers(n);
        auto dfs = [&](auto sfs, int v) -> void {
            int le = outs_start(v);
            int ri = outs_start(v+1);
            int siz = ri - le;
            vector<E> rui(siz+1);
            rui[siz] = e();
            for (int i = siz-1; i >= 0; i--){
                rui[i] = merge(outs[le+i],rui[i+1]);
            }
            answers[v] = put_vertex(merge(rui[0],reverse_edge[v]),v);
            E lui = e();
            for (int i = 0; i < siz; i++){
                V rdp = put_vertex(merge(merge(lui,rui[i+1]),reverse_edge[v]),v);
                reverse_edge[es[start[v]+i].to] = put_edge(rdp,es[start[v]+i].xdi);
                lui = merge(lui,outs[le+i]);
                sfs(sfs,es[start[v]+i].to);
            }
        };
        dfs(dfs,root);
        return answers;
    }
    private:
    int n, root, inner_edge_id;
    vector<E> outs;
    vector<edge> es;
    vector<int> start;
    int outs_start(int v){
        int res = start[v] - v;
        if (root < v) res++;
        return res;
    }
    void es_build(){
        vector<edge> nes(2*n-2);
        vector<int> nstart(n+2,0);
        for (int i = 0; i < 2*n-2; i++) nstart[start[i]+2]++;
        for (int i = 0; i < n; i++) nstart[i+1] += nstart[i];
        for (int i = 0; i < 2*n-2; i++) nes[nstart[start[i]+1]++] = es[i];
        swap(es,nes);
        swap(start,nstart);
    }
};

vector<Edge<ll>> edge;

ll put_vertex(ll e, int i){
	return e;
}
ll merge(ll e1, ll e2){
	return max(e1,e2);
}
ll e(){
	return 0;
}
ll put_edge(ll v, int i){
	return v + edge[i].cost;
}

void solve(){
    int n;
    cin>>n;
    rep(i,n-1){
    	int a,b;
    	cin>>a>>b;
    	a--;
    	b--;
    	ll c;
    	cin>>c;
    	edge.PB({a,b,i,c});
    }
    RerootingDP<ll,ll,merge,e,put_edge,put_vertex> dp(n);
    rep(i,n-1){
    	dp.add_edge(edge[i].from,edge[i].to,i,i);
    }
    dp.build(0);
    vector<ll> res = dp.reroot();
    ll mval = 0;
    rep(i,res.size())chmax(mval,res[i]);
    cout<<mval<<endl;
    
}

signed main(){
	cin.tie(0);
	ios::sync_with_stdio(0);
	cout<<fixed<<setprecision(20);
	int TT; TT = 1; //cin >> TT;
	while(TT--) solve();
}
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