結果

問題 No.2677 Minmax Independent Set
コンテスト
ユーザー dyktr_06
提出日時 2024-03-16 00:50:32
言語 C++17
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 832 ms / 2,000 ms
コード長 7,459 bytes
コンパイル時間 5,053 ms
コンパイル使用メモリ 273,432 KB
最終ジャッジ日時 2025-02-20 06:35:40
ジャッジサーバーID
（参考情報） 		judge4 / judge2
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 * 3
other AC * 61
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>
#include <atcoder/all>

using namespace std;
using namespace atcoder;

#define overload4(_1, _2, _3, _4, name, ...) name
#define rep1(n) for(int i = 0; i < (int)(n); ++i)
#define rep2(i, n) for(int i = 0; i < (int)(n); ++i)
#define rep3(i, a, b) for(int i = (a); i < (int)(b); ++i)
#define rep4(i, a, b, c) for(int i = (a); i < (int)(b); i += (c))
#define rep(...) overload4(__VA_ARGS__, rep4, rep3, rep2, rep1)(__VA_ARGS__)

#define rrep(i,n) for(int i = (int)(n) - 1; i >= 0; --i)
#define ALL(a) (a).begin(), (a).end()
#define Sort(a) (sort((a).begin(), (a).end()))
#define RSort(a) (sort((a).rbegin(), (a).rend()))
#define UNIQUE(a) (a.erase(unique((a).begin(), (a).end()), (a).end()))

typedef long long int ll;
typedef unsigned long long ul;
typedef long double ld;
typedef vector<int> vi;
typedef vector<long long> vll;
typedef vector<char> vc;
typedef vector<string> vst;
typedef vector<double> vd;
typedef vector<long double> vld;
typedef pair<long long, long long> P;

template<class T> long long sum(const T& a){ return accumulate(a.begin(), a.end(), 0LL); }
template<class T> auto min(const T& a){ return *min_element(a.begin(), a.end()); }
template<class T> auto max(const T& a){ return *max_element(a.begin(), a.end()); }

const long long MINF = 0x7fffffffffff;
const long long INF = 0x1fffffffffffffff;
const long long MOD = 998244353;
const long double EPS = 1e-9;
const long double PI = acos(-1);
 
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; }

template<typename T1, typename T2> istream &operator>>(istream &is, pair<T1, T2> &p){ is >> p.first >> p.second; return is; }
template<typename T1, typename T2> ostream &operator<<(ostream &os, const pair<T1, T2> &p){ os << "(" << p.first << ", " << p.second << ")"; return os; }
template<typename T> istream &operator>>(istream &is, vector<T> &v){ for(T &in : v) is >> in; return is; }
template<typename T> ostream &operator<<(ostream &os, const vector<T> &v){ for(int i = 0; i < (int) v.size(); ++i){ os << v[i] << (i + 1 != (int) v.size() ? " " : ""); } return os; }
template <typename T, typename S> ostream &operator<<(ostream &os, const map<T, S> &mp){ for(auto &[key, val] : mp){ os << key << ":" << val << " "; } return os; }
template <typename T> ostream &operator<<(ostream &os, const set<T> &st){ auto itr = st.begin(); for(int i = 0; i < (int)st.size(); ++i){ os << *itr << (i + 1 != (int)st.size() ? " " : ""); itr++; } return os; }
template <typename T> ostream &operator<<(ostream &os, const multiset<T> &st){ auto itr = st.begin(); for(int i = 0; i < (int)st.size(); ++i){ os << *itr << (i + 1 != (int)st.size() ? " " : ""); itr++; } return os; }
template <typename T> ostream &operator<<(ostream &os, queue<T> q){ while(q.size()){ os << q.front() << " "; q.pop(); } return os; }
template <typename T> ostream &operator<<(ostream &os, deque<T> q){ while(q.size()){ os << q.front() << " "; q.pop_front(); } return os; }
template <typename T> ostream &operator<<(ostream &os, stack<T> st){ while(st.size()){ os << st.top() << " "; st.pop(); } return os; }
template <class T, class Container, class Compare> ostream &operator<<(ostream &os, priority_queue<T, Container, Compare> pq){ while(pq.size()){ os << pq.top() << " "; pq.pop(); } return os; }

template<class T, class U> inline T vin(T& vec, U n) { vec.resize(n); for(int i = 0; i < (int) n; ++i) cin >> vec[i]; return vec; }
template<class T> inline void vout(T vec, string s = "\n"){ for(auto x : vec) cout << x << s; }
template<class... T> void in(T&... a){ (cin >> ... >> a); }
void out(){ cout << '\n'; }
template<class T, class... Ts> void out(const T& a, const Ts&... b){ cout << a; (cout << ... << (cout << ' ', b)); cout << '\n'; }
template<class T, class U> void inGraph(vector<vector<T>>& G, U n, U m, bool directed = false){ G.resize(n); for(int i = 0; i < m; ++i){ int a, b; cin >> a >> b; a--, b--; G[a].push_back(b); if(!directed) G[b].push_back(a); } }

template<typename E, typename V>
struct Rerooting{
    struct edge{
        int from, to, idx, rev_idx;
    };
    int n, root;
    vector<vector<edge>> edges;
    vector<int> visited;
    vector<vector<E>> out;
    vector<E> reverse_edge;
    vector<V> ans;
    function<E(E, E)> merge;
    E e;
    function<E(V, int)> put_edge;
    function<V(E, int)> put_vertex;
    Rerooting(int _n, const function<E(E, E)> &_merge, const E &_e, const function<E(V, int)> &_put_edge, const function<V(E, int)> &_put_vertex) : n(_n), merge(_merge), e(_e), put_edge(_put_edge), put_vertex(_put_vertex){
        edges.resize(n);
    }

private:
    V dfs(int v){
        visited[v]++;
        E val = e;
        for(auto &p : edges[v]){
            if(visited[p.to] > 0 && p.to != edges[v].back().to){
                swap(p, edges[v].back());
            }
            if(visited[p.to] > 0) continue;
            E nval = put_edge(dfs(p.to), p.idx);
            out[v].emplace_back(nval);
            val = merge(val, nval);
        }
        return put_vertex(val, v);
    }

    void bfs(int v){
        int siz = out[v].size();
        vector<E> left(siz + 1), right(siz + 1);
        left[0] = e, right[siz] = e;
        for(int i = 0; i < siz; i++){
            left[i + 1] = merge(left[i], out[v][i]);
        }
        for(int i = siz - 1; i >= 0; i--){
            right[i] = merge(out[v][i], right[i + 1]);
        }
        for(int i = 0; i < siz; i++){
            reverse_edge[edges[v][i].to] = put_edge(put_vertex(merge(merge(left[i], right[i + 1]), reverse_edge[v]), v), edges[v][i].rev_idx);
            bfs(edges[v][i].to);
        }
        ans[v] = put_vertex(merge(left[siz], reverse_edge[v]), v);
    }

public:
    void add_edge(int u, int v, int idx1, int idx2){
        edges[u].push_back({u, v, idx1, idx2});
        edges[v].push_back({v, u, idx2, idx1});
    }

    V build(int v = 0){
        root = v;
        out.resize(n);
        visited.assign(n, 0);
        return dfs(root);
    }

    vector<V> reroot(){
        reverse_edge.resize(n);
        reverse_edge[root] = e;
        ans.resize(n);
        bfs(root);
        return ans;
    }
};

ll n;

void input(){
    in(n);
}

// ll solve_sub(ll x){
//     auto dfs = [&](auto &self, ll curr, ll prev) -> vll {
//         vll dp(2);
//         dp[1] = 1;
//         for(auto x : G[curr]){
//             if(x == prev) continue;
//             vll ndp = self(self, x, curr);
//             dp[0] += max(ndp[0], ndp[1]);
//             dp[1] += ndp[0];
//         }
//         return dp;
//     };
//     vll dp = dfs(dfs, x, -1);
//     return dp[1];
// }

void solve(){
    using T = vll;
    auto merge = [&](T x, T y){
        T res = {x[0] + y[0], x[1] + y[1]};
        return res;
    };
    auto put_edge = [&](T x, int i){
        T res = {max(x[0], x[1]), x[0]};
        return res;
    };
    auto put_vertex = [&](T e, int v){
        T res = {e[0], e[1] + 1};
        return res;
    };
    T e = {0LL, 0LL};
    Rerooting<T, T> G(n, merge, e, put_edge, put_vertex);
    rep(i, n - 1){
        ll a, b; in(a, b); a--, b--;
        G.add_edge(a, b, i, i);
    }
    G.build();
    ll ans = INF;
    for(auto x : G.reroot()){
        chmin(ans, x[1]);
    }
    out(ans);
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout << fixed << setprecision(20);
    
    input();
    solve();
}
0