結果

問題 No.1833 Subway Planning
ユーザー SumitacchanSumitacchan
提出日時 2022-02-04 23:39:34
言語 C++17
(gcc 13.3.0 + boost 1.87.0)
結果
WA  
実行時間 -
コード長 5,309 bytes
コンパイル時間 3,053 ms
コンパイル使用メモリ 215,208 KB
最終ジャッジ日時 2025-01-27 20:06:27
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
（要ログイン）
ファイルパターン 結果
sample AC * 1 WA * 2
other AC * 14 WA * 9
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 # 

#include <bits/stdc++.h>
using namespace std;
//using namespace atcoder;
struct fast_ios { fast_ios(){ cin.tie(0); ios::sync_with_stdio(false); cout << fixed << setprecision(20); }; } fast_ios_;
#define FOR(i, begin, end) for(int i=(begin);i<(end);i++)
#define REP(i, n) FOR(i,0,n)
#define IFOR(i, begin, end) for(int i=(end)-1;i>=(begin);i--)
#define IREP(i, n) IFOR(i,0,n)
#define Sort(v) sort(v.begin(), v.end())
#define Reverse(v) reverse(v.begin(), v.end())
#define all(v) v.begin(),v.end()
#define SZ(v) ((int)v.size())
#define Lower_bound(v, x) distance(v.begin(), lower_bound(v.begin(), v.end(), x))
#define Upper_bound(v, x) distance(v.begin(), upper_bound(v.begin(), v.end(), x))
#define chmax(a, b) a = max(a, b)
#define chmin(a, b) a = min(a, b)
#define bit(n) (1LL<<(n))
#define debug(x) cout << #x << "=" << x << endl;
#define vdebug(v) { cout << #v << "=" << endl; REP(i_debug, (int)v.size()){ cout << v[i_debug] << ","; } cout << endl; }
#define mdebug(m) { cout << #m << "=" << endl; REP(i_debug, (int)m.size()){ REP(j_debug, (int)m[i_debug].size()){ cout << m[i_debug][j_debug] << ","; } cout << endl;} }
#define pb push_back
#define fi first
#define se second
#define int long long
#define INF 1000000000000000000
template<typename T> istream &operator>>(istream &is, vector<T> &v){ for (auto &x : v) is >> x; return is; }
template<typename T> ostream &operator<<(ostream &os, vector<T> &v){ for(int i = 0; i < (int)v.size(); i++) { cout << v[i]; if(i != (int)v.size() - 1) cout << endl; }; return os; }
template<typename T1, typename T2> ostream &operator<<(ostream &os, pair<T1, T2> p){ cout << '(' << p.first << ',' << p.second << ')'; return os; }
template<typename T> void Out(T x) { cout << x << endl; }
template<typename T1, typename T2> void chOut(bool f, T1 y, T2 n) { if(f) Out(y); else Out(n); }

using vec = vector<int>;
using mat = vector<vec>;
using Pii = pair<int, int>;
using v_bool = vector<bool>;
using v_Pii = vector<Pii>;

//int dx[4] = {1,0,-1,0};
//int dy[4] = {0,1,0,-1};
//char d[4] = {'D','R','U','L'};

//const int mod = 1000000007;
const int mod = 998244353;

struct SegmentTree
{
    using T = int;

    int N;
    vector<T> dat;

    T id = -1;
    T F(T &a, T &b) { return max(a, b); }
    
    SegmentTree(int n){
        N = 1;
        while(n > N) N = N << 1;
        dat = vector<T>(2 * N - 1, id);
    }

    SegmentTree(int n, vector<T> &v){
        N = 1;
        while(n > N) N = N << 1;
        dat = vector<T>(2 * N - 1, id);
        for(int i = 0; i < n; i++) dat[i + N - 1] = v[i];
        for(int i = N - 2; i >= 0; i--) dat[i] = F(dat[i * 2 + 1], dat[i * 2 + 2]); 
    }

    SegmentTree(){}


    void update(int k, T a){
        k += N - 1;
        dat[k] = a;
        while(k > 0){
            k = (k - 1) / 2;
            dat[k] = F(dat[k * 2 + 1], dat[k * 2 + 2]);
        }
    }

    void reset() { fill(dat.begin(), dat.end(), id); }

    T get(int a, int b, int k, int l, int r){
        if(r <= a || b <= l) return id;
        if(a <= l && r <= b) return dat[k];
        else{
            T vl = get(a, b, k * 2 + 1, l, (l + r) / 2);
            T vr = get(a, b, k * 2 + 2, (l + r) / 2, r);
            return F(vl, vr);
        }
    }
    T get(int a, int b) { return get(a, b, 0, 0, N); }

    T val(int k){ return dat[k + N - 1]; }
};

template<typename T> 
struct edge{ int to; T cost; int id; };

template<typename T = long long>
struct Graph
{

    int N;
    vector<vector<edge<T>>> E;
    vec vs, es, mid, Mid;
    vec mcost;
    v_Pii q;

    Graph(int N): N(N){
        E = vector<vector<edge<T>>>(N, vector<edge<T>>(0));
        mid = vec(N, INF);
        Mid = vec(N, -INF);
        mcost = vec(N - 1, 0);
    }

    void add_Directed_edge(int from, int to, T cost = 1, int id = 0){
        E[from].push_back(edge<T>({ to, cost, id }));
    }

    void add_Undirected_edge(int v1, int v2, T cost = 1, int id = 0){
        add_Directed_edge(v1, v2, cost, id);
        add_Directed_edge(v2, v1, cost, id);
    }

    void dfs1(int v, int p = -1){
        vs.pb(v);
        mid[v] = Mid[v] = SZ(vs) - 1;
        for(auto e: E[v]) if(e.to != p){
            es.pb(e.cost);
            dfs1(e.to, v);
            es.pb(e.cost);
            vs.pb(v);
            Mid[v] = SZ(vs) - 1;
        }
    }

    void dfs2(int v, SegmentTree &ST, int p = -1){
        for(auto e: E[v]) if(e.to != p){
            int m_in = ST.get(mid[e.to], Mid[e.to]);
            int m_out = max(ST.get(0, mid[e.to]), ST.get(Mid[e.to], SZ(es)));
            mcost[e.id] = max(e.cost, min(m_in, m_out));
            dfs2(e.to, ST, v);

            q.pb(Pii(mcost[e.id], e.cost));
        }
    }


};

signed main(){

    int N; cin >> N;
    Graph G(N);
    vec cs;
    REP(i, N - 1){
        int a, b, c; cin >> a >> b >> c;
        a--; b--;
        G.add_Undirected_edge(a, b, c, i);
        cs.pb(c);
    }
    G.dfs1(0);
    SegmentTree ST(SZ(G.es), G.es);
    G.dfs2(0, ST);
    //vdebug(G.mcost);

    auto q = G.q;
    Sort(q); Reverse(q);
    cs.pb(0);
    Sort(cs); Reverse(cs);

    int ans = INF, val = INF;
    int j = 0;
    REP(i, SZ(cs) - 1){
        while(j < SZ(q) && q[j].fi >= cs[i]){
            chmin(val, q[j].se);
            j++;
        }
        chmin(ans, max(cs[i + 1], cs[0] - val));
    }
    Out(ans);

    return 0;
}
0