#1105497 (C++17) No.3206 う　し　た　ウ　ニ　木　あ　く　ん　笑

提出ソース
結果

問題	No.3206 う　し　た　ウ　ニ　木　あ　く　ん　笑
コンテスト
ユーザー	👑 potato167
提出日時	2025-07-18 21:43:07
言語	C++17 (gcc 13.3.0 + boost 1.87.0)
結果	AC
実行時間	542 ms / 3,000 ms
コード長	14,330 bytes
コンパイル時間	2,715 ms
コンパイル使用メモリ	227,728 KB
実行使用メモリ	125,252 KB
最終ジャッジ日時	2025-07-18 21:43:20
合計ジャッジ時間	9,418 ms
ジャッジサーバーID （参考情報）	judge3 / judge4
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 * 2
other	AC * 30
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

raw source code
//#include <bits/stdc++.h>
//using namespace std;
//using ll=long long;
//const ll ILL=2167167167167167167;
//const int INF=2100000000;
//#define rep(i,a,b) for (int i=(int)(a);i<(int)(b);i++)
//#define all(p) p.begin(),p.end()
//template<class T> using _pq = priority_queue<T, vector<T>, greater<T>>;
//template<class T> int LB(vector<T> &v,T a){return lower_bound(v.begin(),v.end(),a)-v.begin();}
//template<class T> int UB(vector<T> &v,T a){return upper_bound(v.begin(),v.end(),a)-v.begin();}
//template<class T> bool chmin(T &a,T b){if(b<a){a=b;return 1;}else return 0;}
//template<class T> bool chmax(T &a,T b){if(a<b){a=b;return 1;}else return 0;}
//template<class T> void So(vector<T> &v) {sort(v.begin(),v.end());}
//template<class T> void Sore(vector<T> &v) {sort(v.begin(),v.end(),[](T x,T y){return x>y;});}
//bool yneos(bool a,bool upp=false){if(a){cout<<(upp?"YES\n":"Yes\n");}else{cout<<(upp?"NO\n":"No\n");}return a;}
//template<class T> void vec_out(vector<T> &p,int ty=0){
//    if(ty==2){cout<<'{';for(int i=0;i<(int)p.size();i++){if(i){cout<<",";}cout<<'"'<<p[i]<<'"';}cout<<"}\n";}
//    else{if(ty==1){cout<<p.size()<<"\n";}for(int i=0;i<(int)(p.size());i++){if(i) cout<<" ";cout<<p[i];}cout<<"\n";}}
//template<class T> T vec_min(vector<T> &a){assert(!a.empty());T ans=a[0];for(auto &x:a) chmin(ans,x);return ans;}
//template<class T> T vec_max(vector<T> &a){assert(!a.empty());T ans=a[0];for(auto &x:a) chmax(ans,x);return ans;}
//template<class T> T vec_sum(vector<T> &a){T ans=T(0);for(auto &x:a) ans+=x;return ans;}
//int pop_count(long long a){int res=0;while(a){res+=(a&1),a>>=1;}return res;}
//template<class T> T square(T a){return a * a;}
//
////https://trap.jp/post/1702/
//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 from, to, idx, rev_idx;
//    };
//    RerootingDP (int _n = 0) : n(_n) { es.resize(n);}
//    void add_edge(int u, int v, int idx1, int idx2){
//        es[u].push_back({u,v,idx1,idx2});
//        es[v].push_back({v,u,idx2,idx1});
//    }
//    V build(int v = 0){
//        root = v;
//        vis.resize(n,0);
//        outs.resize(n);
//        return dfs(root);
//    }
//    vector<V> reroot(){
//        reverse_edge.resize(n);
//        reverse_edge[root] = e();
//        answers.resize(n);
//        bfs(root);
//        return answers;
//    }
//private:
//    int n, root;
//    vector<vector<edge>> es;
//    vector<int> vis;
//    vector<vector<E>> outs;
//    vector<E> reverse_edge;
//    vector<V> answers;
//    V dfs(int v){
//        vis[v]++;
//        E val = e();
//        for (auto &p : es[v]){
//            if (vis[p.to] > 0 && p.to != es[v].back().to) swap(p,es[v].back());
//            if (vis[p.to] > 0) continue;
//            E nval = put_edge(dfs(p.to),p.idx);
//            outs[v].emplace_back(nval);
//            val = merge(val,nval);
//        }
//        return put_vertex(val,v);
//    }
//    void bfs(int v){
//        int siz = outs[v].size();
//        vector<E> lui(siz+1), rui(siz+1);
//        lui[0] = e(), rui[siz] = e();
//        for (int i = 0; i < siz; i++) lui[i+1] = merge(lui[i],outs[v][i]);
//        for (int i = siz-1; i >= 0; i--) rui[i] = merge(outs[v][i],rui[i+1]);
//        for (int i = 0; i < siz; i++){
//            reverse_edge[es[v][i].to] = put_edge(put_vertex(merge(merge(lui[i],rui[i+1]),reverse_edge[v]),v),es[v][i].rev_idx);
//            bfs(es[v][i].to);
//        }
//        answers[v] = put_vertex(merge(lui[siz],reverse_edge[v]), v);
//    }
//};
//
//using reroot_F=array<pair<int, int>, 2>;
//
//reroot_F merge(reroot_F a, reroot_F b){
//    reroot_F res;
//    int x = 0, y = 0;
//    rep(i, 0, 2){
//        if (a[x] > b[y]) res[i] = a[x++];
//        else res[i] = b[y++];
//    }
//    return res;
//}
//reroot_F e(){
//    pair<int, int> tmp = {-INF, -INF};
//    return {tmp, tmp};
//}
//reroot_F put_edge(reroot_F v, int i){
//    for (auto &x : v) x.first++;
//    v[1] = {-INF, -INF};
//    return v;
//}
//reroot_F put_vertex(reroot_F e, int v){
//    pair<int, int> tmp = {0, v};
//    if (chmax(e[1], tmp)){
//        if (e[0] < e[1]) swap(e[0], e[1]);
//    }
//    return e;
//}
//#define reroot_calc reroot_F,reroot_F,merge,e,put_edge,put_vertex
//
//#include "po167_library/graph/tree/LCA.hpp"
//
//void solve();
//// POP'N ROLL MUSIC / TOMOO
//int main() {
//    ios::sync_with_stdio(false);
//    cin.tie(nullptr);
//
//    int t = 1;
//    // cin >> t;
//    rep(i, 0, t) solve();
//}
//
//void solve(){
//    int N;
//    cin >> N;
//    vector<vector<int>> G(N);
//    RerootingDP<reroot_calc> R(N);
//    rep(i, 0, N - 1){
//        int a, b;
//        cin >> a >> b;
//        a--, b--;
//        G[a].push_back(b);
//        G[b].push_back(a);
//        R.add_edge(a, b, i, i);
//    }
//    po167::LCA L(G);
//    R.build();
//    int ans = 0;
//    auto res = R.reroot();
//    // for (auto a : res) cout << a[0].first << " " << a[0].second << " " << a[1].first << " " << a[1].second << "\n";
//    rep(i, 0, N){
//        vector<int> p;
//        for (auto x : G[i]){
//            if (L.dist(x, res[x][0].second) - 1 == L.dist(i, res[x][0].second)) p.push_back(res[x][1].first);
//            else p.push_back(res[x][0].first);
//        }
//        Sore(p);
//        // vec_out(p);
//        rep(j, 0, p.size()){
//            chmax(ans, 1 + (p[j] + 1) * (j + 1));
//        }
//    }
//    cout << ans << "\n";
//}
//
#line 1 "d.cpp"
#include <bits/stdc++.h>
using namespace std;
using ll=long long;
const ll ILL=2167167167167167167;
const int INF=2100000000;
#define rep(i,a,b) for (int i=(int)(a);i<(int)(b);i++)
#define all(p) p.begin(),p.end()
template<class T> using _pq = priority_queue<T, vector<T>, greater<T>>;
template<class T> int LB(vector<T> &v,T a){return lower_bound(v.begin(),v.end(),a)-v.begin();}
template<class T> int UB(vector<T> &v,T a){return upper_bound(v.begin(),v.end(),a)-v.begin();}
template<class T> bool chmin(T &a,T b){if(b<a){a=b;return 1;}else return 0;}
template<class T> bool chmax(T &a,T b){if(a<b){a=b;return 1;}else return 0;}
template<class T> void So(vector<T> &v) {sort(v.begin(),v.end());}
template<class T> void Sore(vector<T> &v) {sort(v.begin(),v.end(),[](T x,T y){return x>y;});}
bool yneos(bool a,bool upp=false){if(a){cout<<(upp?"YES\n":"Yes\n");}else{cout<<(upp?"NO\n":"No\n");}return a;}
template<class T> void vec_out(vector<T> &p,int ty=0){
    if(ty==2){cout<<'{';for(int i=0;i<(int)p.size();i++){if(i){cout<<",";}cout<<'"'<<p[i]<<'"';}cout<<"}\n";}
    else{if(ty==1){cout<<p.size()<<"\n";}for(int i=0;i<(int)(p.size());i++){if(i) cout<<" ";cout<<p[i];}cout<<"\n";}}
template<class T> T vec_min(vector<T> &a){assert(!a.empty());T ans=a[0];for(auto &x:a) chmin(ans,x);return ans;}
template<class T> T vec_max(vector<T> &a){assert(!a.empty());T ans=a[0];for(auto &x:a) chmax(ans,x);return ans;}
template<class T> T vec_sum(vector<T> &a){T ans=T(0);for(auto &x:a) ans+=x;return ans;}
int pop_count(long long a){int res=0;while(a){res+=(a&1),a>>=1;}return res;}
template<class T> T square(T a){return a * a;}

//https://trap.jp/post/1702/
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 from, to, idx, rev_idx;
    };
    RerootingDP (int _n = 0) : n(_n) { es.resize(n);}
    void add_edge(int u, int v, int idx1, int idx2){
        es[u].push_back({u,v,idx1,idx2});
        es[v].push_back({v,u,idx2,idx1});
    }
    V build(int v = 0){
        root = v;
        vis.resize(n,0);
        outs.resize(n);
        return dfs(root);
    }
    vector<V> reroot(){
        reverse_edge.resize(n);
        reverse_edge[root] = e();
        answers.resize(n);
        bfs(root);
        return answers;
    }
private:
    int n, root;
    vector<vector<edge>> es;
    vector<int> vis;
    vector<vector<E>> outs;
    vector<E> reverse_edge;
    vector<V> answers;
    V dfs(int v){
        vis[v]++;
        E val = e();
        for (auto &p : es[v]){
            if (vis[p.to] > 0 && p.to != es[v].back().to) swap(p,es[v].back());
            if (vis[p.to] > 0) continue;
            E nval = put_edge(dfs(p.to),p.idx);
            outs[v].emplace_back(nval);
            val = merge(val,nval);
        }
        return put_vertex(val,v);
    }
    void bfs(int v){
        int siz = outs[v].size();
        vector<E> lui(siz+1), rui(siz+1);
        lui[0] = e(), rui[siz] = e();
        for (int i = 0; i < siz; i++) lui[i+1] = merge(lui[i],outs[v][i]);
        for (int i = siz-1; i >= 0; i--) rui[i] = merge(outs[v][i],rui[i+1]);
        for (int i = 0; i < siz; i++){
            reverse_edge[es[v][i].to] = put_edge(put_vertex(merge(merge(lui[i],rui[i+1]),reverse_edge[v]),v),es[v][i].rev_idx);
            bfs(es[v][i].to);
        }
        answers[v] = put_vertex(merge(lui[siz],reverse_edge[v]), v);
    }
};

using reroot_F=array<pair<int, int>, 2>;

reroot_F merge(reroot_F a, reroot_F b){
    reroot_F res;
    int x = 0, y = 0;
    rep(i, 0, 2){
        if (a[x] > b[y]) res[i] = a[x++];
        else res[i] = b[y++];
    }
    return res;
}
reroot_F e(){
    pair<int, int> tmp = {-INF, -INF};
    return {tmp, tmp};
}
reroot_F put_edge(reroot_F v, int i){
    for (auto &x : v) x.first++;
    v[1] = {-INF, -INF};
    return v;
}
reroot_F put_vertex(reroot_F e, int v){
    pair<int, int> tmp = {0, v};
    if (chmax(e[1], tmp)){
        if (e[0] < e[1]) swap(e[0], e[1]);
    }
    return e;
}
#define reroot_calc reroot_F,reroot_F,merge,e,put_edge,put_vertex

#line 4 "/Users/Shared/po167_library/ds/Sparse_table.hpp"
namespace po167{
template<class T, T(*op)(T, T)>
struct Sparse_table{
    int n;
    int depth;
    std::vector<std::vector<T>> val;
    void init(std::vector<T> &v){
        depth = 1;
        n = v.size();
        while ((1 << depth) <= n) depth++;
        val.resize(depth);
        val[0] = v;
        for (int i = 1; i < depth; i++){
            val[i].resize(n);
            for (int j = 0; j <= n - (1 << i); j++){
                val[i][j] = op(val[i - 1][j], val[i - 1][j + (1 << (i - 1))]);
            }
        }
    }
    Sparse_table(std::vector<T> v){
        init(v);
    }
    Sparse_table(){}
    // 0 <= l < r <= n
    // if l == r : assert
    T prod(int l, int r){
        assert(0 <= l && l < r && r <= n);
        int z=31-__builtin_clz(r-l);
        return op(val[z][l], val[z][r - (1 << z)]);
    }
};
}
#line 6 "/Users/Shared/po167_library/graph/tree/LCA.hpp"
namespace po167{
int op(int a, int b){
    return std::min(a, b);
}
struct LCA{
    Sparse_table<int, op> table;
    std::vector<int> depth;
    std::vector<int> E;
    std::vector<int> order;
    int var_num;
    void init(std::vector<std::vector<int>> &g, int root = 0){
        var_num = g.size();
        assert(0 <= root && root < var_num);
        std::vector<int> val;
        depth.assign(var_num, -1);
        depth[root] = 0;
        E.resize(var_num);
        std::vector<int> tmp;
        order.clear();
        tmp.reserve(var_num);
        order.reserve(var_num);
        int c = 0;
        auto dfs = [&](auto self, int var, int pare) -> void {
            E[var] = c++;
            if (var != root) tmp.push_back(E[pare]);
            order.push_back(var);
            for (auto x : g[var]) if (depth[x] == -1){
                depth[x] = depth[var] + 1;
                self(self, x, var);
            }
        };
        dfs(dfs, root, -1);
        assert(c == var_num);
        table.init(tmp);
    }
    void init(std::vector<int> &pare){
        int root = -1;
        int n = pare.size();
        std::vector<std::vector<int>> g(n);
        for (int i = 0; i < n; i++){
            if (pare[i] < 0){
                assert(root == -1);
                root = i;
            }
            else{
                assert(0 <= pare[i] && pare[i] < n);
                g[pare[i]].push_back(i);
            }
        }
        assert(root != -1);
        init(g, root);
    }
    LCA (std::vector<std::vector<int>> g, int root = 0){
        init(g, root);
    }
    LCA (std::vector<int> pare){
        init(pare);
    }
    LCA(){
        
    }
    int lca(int a, int b){
        assert(0 <= std::min(a, b) && std::max(a, b) < var_num);
        if (a == b) return a;
        if (E[a] > E[b]) std::swap(a, b);
        return order[table.prod(E[a], E[b])];
    }
    int dist(int a, int b){
        assert(0 <= std::min(a, b) && std::max(a, b) < var_num);
        return depth[a] + depth[b] - 2 * depth[lca(a, b)];
    }
    int back(int var, int len){
        assert(len <= depth[var]);
        if (len == 0) return var;
        int l = 0, r = E[var];
        while (r - l > 1){
            int m = (l + r) / 2;
            if (depth[var] - depth[order[table.prod(m, E[var])]] < len){
                r = m;
            }
            else l = m;
        }
        return order[table.prod(l, E[var])];
    }
    // a -> b
    int jump(int a, int b, int len){
        int c = lca(a, b);
        if (len <= depth[a] - depth[c]) return back(a, len);
        len -= depth[a] - depth[c];
        if (len <= depth[b] - depth[c]) return back(b, depth[b] - depth[c] - len);
        return -1;
    }
};

}
#line 112 "d.cpp"

void solve();
// POP'N ROLL MUSIC / TOMOO
int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int t = 1;
    // cin >> t;
    rep(i, 0, t) solve();
}

void solve(){
    int N;
    cin >> N;
    vector<vector<int>> G(N);
    RerootingDP<reroot_calc> R(N);
    rep(i, 0, N - 1){
        int a, b;
        cin >> a >> b;
        a--, b--;
        G[a].push_back(b);
        G[b].push_back(a);
        R.add_edge(a, b, i, i);
    }
    po167::LCA L(G);
    R.build();
    int ans = 0;
    auto res = R.reroot();
    // for (auto a : res) cout << a[0].first << " " << a[0].second << " " << a[1].first << " " << a[1].second << "\n";
    rep(i, 0, N){
        vector<int> p;
        for (auto x : G[i]){
            if (L.dist(x, res[x][0].second) - 1 == L.dist(i, res[x][0].second)) p.push_back(res[x][1].first);
            else p.push_back(res[x][0].first);
        }
        Sore(p);
        // vec_out(p);
        rep(j, 0, p.size()){
            chmax(ans, 1 + (p[j] + 1) * (j + 1));
        }
    }
    cout << ans << "\n";
}
yukicoder

結果

ソースコード
