結果

問題 No.1833 Subway Planning
ユーザー oteraotera
提出日時 2022-02-05 06:03:14
言語 C++17
(gcc 12.3.0 + boost 1.83.0)
結果
WA  
実行時間 -
コード長 11,250 bytes
コンパイル時間 2,850 ms
コンパイル使用メモリ 225,916 KB
実行使用メモリ 51,320 KB
最終ジャッジ日時 2023-09-02 06:27:29
合計ジャッジ時間 8,811 ms
ジャッジサーバーID
（参考情報） 		judge12 / judge14
このコードへのチャレンジ
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テストケース

テストケース表示
入力 結果 実行時間
実行使用メモリ
testcase_00 WA -
testcase_01 AC 2 ms
4,380 KB
testcase_02 WA -
testcase_03 AC 1 ms
4,380 KB
testcase_04 AC 143 ms
51,140 KB
testcase_05 AC 146 ms
51,320 KB
testcase_06 AC 246 ms
51,208 KB
testcase_07 WA -
testcase_08 WA -
testcase_09 WA -
testcase_10 AC 249 ms
46,152 KB
testcase_11 WA -
testcase_12 AC 143 ms
36,664 KB
testcase_13 AC 252 ms
46,044 KB
testcase_14 WA -
testcase_15 AC 164 ms
36,148 KB
testcase_16 AC 194 ms
36,452 KB
testcase_17 WA -
testcase_18 WA -
testcase_19 WA -
testcase_20 AC 138 ms
28,900 KB
testcase_21 AC 275 ms
49,324 KB
testcase_22 AC 278 ms
46,592 KB
testcase_23 AC 2 ms
4,376 KB
testcase_24 AC 2 ms
4,376 KB
testcase_25 AC 1 ms
4,376 KB
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 # 

/**
 *    author:  otera
 *    created: 05.02.2022 03:04:09 
**/
#include<bits/stdc++.h>
#include<atcoder/dsu>
#include<vector>

namespace otera {
    class LCA {
        public:
            LCA(const std::vector<std::vector<int>> &g, int root = 0) {
                int _n = (int)g.size();
                int _N = 1;
                while((1<<_N) < _n) ++ _N;
                parent.assign(_N, std::vector<int>(_n, -1));
                dep.assign(_n, -1);
                dfs(g, root);
                for(int i = 0; i + 1 < (int)parent.size(); ++ i) {
                    for(int v = 0; v < _n; ++ v) {
                        if(parent[i][v] != -1) {
                            parent[i + 1][v] = parent[i][parent[i][v]];
                        }
                    }
                }
            }
            
            int lca(int u, int v) const {
                if(dep[u] > dep[v]) std::swap(u, v);
                for(int i = 0; i < (int)parent.size(); ++ i) {
                    if((dep[u] - dep[v]) & (1<<i)) {
                        v = parent[i][v];
                    }
                }
                if(u == v) return u;
                for(int i = (int)parent.size() - 1; i >= 0; -- i) {
                    if(parent[i][u] != parent[i][v]) {
                        u = parent[i][u];
                        v = parent[i][v];
                    }
                }
                return parent[0][u];
            }
            int depth(int u) const { return dep[u]; }
            int dist(int u, int v) const { return dep[u] + dep[v] - 2 * dep[operator()(u, v)]; }
            int operator()(int u, int v) const { return lca(u, v); }
        private:
            std::vector<int> dep;
            std::vector<std::vector<int>> parent;

            void dfs(const std::vector<std::vector<int>> &g, int root) {
                auto rec = [&](auto &&self, int v, int p, int d) -> void {
                    dep[v] = d;
                    parent[0][v] = p;
                    for(int nv: g[v]) {
                        if(nv == p) continue;
                        self(self, nv, v, d + 1);
                    }
                };
                rec(rec, root, -1, 0);
            }
    };
} // namespace otera
namespace otera {
    template <typename T>
    struct Compressor {
        public:
            static constexpr int absent = -1;

            Compressor() : _xs(std::vector<T>{}) {}

            Compressor(const std::vector<T> &vs) {
                add(vs);
                build();
            }

            void add(const std::vector<T> &vs) {
                std::copy(vs.begin(), vs.end(), std::back_inserter(_xs));
            }

            void add(const T &e) {
                _xs.emplace_back(e);
            }

            void build() {
                std::sort(_xs.begin(), _xs.end());
                _xs.erase(std::unique(_xs.begin(), _xs.end()), _xs.end());
            }

            int size() const {
                return _xs.size();
            }

            bool has_key(const T &e) const {
                return std::binary_search(_xs.begin(), _xs.end(), e);
            }

            std::vector<int> get(const std::vector<T> &vs) const {
                std::vector<int> res;
                std::transform(vs.begin(), vs.end(), std::back_inserter(res), [&](const T &e) {
                    return get(e);
                });
                return res;
            }

            int get(const T &e, int default_value = absent) const {
                const int id = min_geq_index(e);
                return id != size() and _xs[id] == e ? id : default_value;
            }

            const T &operator[](int compressed_index) const {
                return _xs[compressed_index];
            }

            T min_gt(const T &e, const T &default_value) const {
                auto it = std::upper_bound(_xs.begin(), _xs.end(), e);
                return it == _xs.end() ? default_value : *it;
            }
            T min_geq(const T &e, const T &default_value) const {
                auto it = std::lower_bound(_xs.begin(), _xs.end(), e);
                return it == _xs.end() ? default_value : *it;
            }
            T max_lt(const T &e, const T &default_value) const {
                auto it = std::lower_bound(_xs.begin(), _xs.end(), e);
                return it == _xs.begin() ? default_value : *std::prev(it);
            }
            T max_leq(const T &e, const T &default_value) const {
                auto it = std::upper_bound(_xs.begin(), _xs.end(), e);
                return it == _xs.begin() ? default_value : *std::prev(it);
            }
            int min_gt_index(const T &e) const {
                return std::upper_bound(_xs.begin(), _xs.end(), e) - _xs.begin();
            }
            int min_geq_index(const T &e) const {
                return std::lower_bound(_xs.begin(), _xs.end(), e) - _xs.begin();
            }
            int max_lt_index(const T &e) const {
                return int(std::lower_bound(_xs.begin(), _xs.end(), e)- _xs.begin()) - 1;
            }
            int max_leq_index(const T &e) const {
                return int(std::lower_bound(_xs.begin(), _xs.end(), e)- _xs.begin()) - 1;
            }
        private:
            std::vector<T> _xs;
    };
} // namespace otera
using namespace std;

using ll = long long;
using ld = long double;
using ull = unsigned long long;
using uint = unsigned;
#define repa(i, n) for(int i = 0; i < n; ++ i)
#define repb(i, a, b) for(int i = a; i < b; ++ i)
#define repc(i, a, b, c) for(int i = a; i < b; i += c)
#define overload4(a, b, c, d, e, ...) e
#define rep(...) overload4(__VA_ARGS__, repc, repb, repa)(__VA_ARGS__)
#define rep1a(i, n) for(int i = 0; i <= n; ++ i)
#define rep1b(i, a, b) for(int i = a; i <= b; ++ i)
#define rep1c(i, a, b, c) for(int i = a; i <= b; i += c)
#define rep1(...) overload4(__VA_ARGS__, rep1c, rep1b, rep1a)(__VA_ARGS__)
#define per(i,n) for(int i=n-1;i>=0;i--)
#define per1(i,n) for(int i=n;i>=1;i--)
typedef pair<int, int> P;
typedef pair<ll, ll> LP;
#define pb push_back
#define eb emplace_back
#define fr first
#define sc second
#define all(c) c.begin(),c.end()
#define lb(c, x) distance((c).begin(), lower_bound(all(c), (x)))
#define ub(c, x) distance((c).begin(), upper_bound(all(c), (x)))
#define Sort(a) sort(all(a))
#define Rev(a) reverse(all(a))
#define Uniq(a) sort(all(a));a.erase(unique(all(a)),end(a))
#define si(c) (int)(c).size()
inline ll popcnt(ull a){ return __builtin_popcountll(a); }
#define tpow(n) (1LL<<(n))
#define unless(A) if(!(A))
ll intpow(ll a, ll b){ ll ans = 1; while(b){ if(b & 1) ans *= a; a *= a; b /= 2; } return ans; }
ll intpow(ll a, ll b, ll m) {ll ans = 1; while(b){ if(b & 1) (ans *= a) %= m; (a *= a) %= m; b /= 2; } return ans; }
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; }
#define INT(...) int __VA_ARGS__;in(__VA_ARGS__)
#define LL(...) ll __VA_ARGS__;in(__VA_ARGS__)
#define ULL(...) ull __VA_ARGS__;in(__VA_ARGS__)
#define STR(...) string __VA_ARGS__;in(__VA_ARGS__)
#define CHR(...) char __VA_ARGS__;in(__VA_ARGS__)
#define DBL(...) double __VA_ARGS__;in(__VA_ARGS__)
#define LD(...) ld __VA_ARGS__;in(__VA_ARGS__)
#define vec(type,name,...) vector<type>name(__VA_ARGS__)
#define VEC(type,name,size) vector<type>name(size);in(name)
#define vv(type,name,h,...) vector<vector<type>>name(h,vector<type>(__VA_ARGS__))
#define VV(type,name,h,w) vector<vector<type>>name(h,vector<type>(w));in(name)
#define vvv(type,name,h,w,...) vector<vector<vector<type>>>name(h,vector<vector<type>>(w,vector<type>(__VA_ARGS__)))
template <class T> using vc = vector<T>;
template <class T> using vvc = vector<vc<T>>;
template <class T> using vvvc = vector<vvc<T>>;
template <class T> using vvvvc = vector<vvvc<T>>;
template <class T> using pq = priority_queue<T>;
template <class T> using pqg = priority_queue<T, vector<T>, greater<T>>;
template<class T> void scan(T& a){ cin >> a; }
template<class T> void scan(vector<T>& a){ for(auto&& i : a) scan(i); }
void in(){}
template <class Head, class... Tail> void in(Head& head, Tail&... tail){ scan(head); in(tail...); }
void print(){ cout << ' '; }
template<class T> void print(const T& a){ cout << a; }
template<class T> void print(const vector<T>& a){ if(a.empty()) return; print(a[0]); for(auto i = a.begin(); ++i != a.end(); ){ cout << ' '; print(*i); } }
int out(){ cout << '\n'; return 0; }
template<class T> int out(const T& t){ print(t); cout << '\n'; return 0; }
template<class Head, class... Tail> int out(const Head& head, const Tail&... tail){ print(head); cout << ' '; out(tail...); return 0; }
#define CHOOSE(a) CHOOSE2 a
#define CHOOSE2(a0,a1,a2,a3,a4,x,...) x
#define debug_1(x1) cout<<#x1<<": "<<x1<<endl
#define debug_2(x1,x2) cout<<#x1<<": "<<x1<<", "#x2<<": "<<x2<<endl
#define debug_3(x1,x2,x3) cout<<#x1<<": "<<x1<<", "#x2<<": "<<x2<<", "#x3<<": "<<x3<<endl
#define debug_4(x1,x2,x3,x4) cout<<#x1<<": "<<x1<<", "#x2<<": "<<x2<<", "#x3<<": "<<x3<<", "#x4<<": "<<x4<<endl
#define debug_5(x1,x2,x3,x4,x5) cout<<#x1<<": "<<x1<<", "#x2<<": "<<x2<<", "#x3<<": "<<x3<<", "#x4<<": "<<x4<<", "#x5<<": "<<x5<<endl
#ifdef DEBUG
#define debug(...) CHOOSE((__VA_ARGS__,debug_5,debug_4,debug_3,debug_2,debug_1,~))(__VA_ARGS__)
#define dump(...) { print(#__VA_ARGS__); print(":"); out(__VA_ARGS__); }
#else
#define debug(...)
#define dump(...)
#endif

// #define int long long

typedef pair<int, P> P2;

void solve() {
    INT(n);
    vvc<int> g(n);
    int cma = 0;
    otera::Compressor<int> cmp;
    vc<P2> es;
    rep(i, n - 1) {
        INT(a, b, c); -- a, -- b;
        g[a].eb(b);
        g[b].eb(a);
        es.eb(c, P{a, b});
        chmax(cma, c);
        cmp.add(c);
    }
    cmp.build();
    int sz = si(cmp);
    vvc<P> h(sz);
    rep(i, n - 1) {
        int a = es[i].sc.fr, b = es[i].sc.sc;
        int c = es[i].fr;
        int cid = cmp.get(c);
        h[cid].eb(a, b);
    }
    atcoder::dsu uf(n);
    otera::LCA lca(g);
    int ans = cma;
    vc<int> deg(n);
    bool check = 1;
    vc<int> cnt(n, 0);
    int pre = 0;
    per(i, sz) {
        int c = cmp[i];
        for(auto [a, b]: h[i]) {
            int sum = cnt[uf.leader(a)] + cnt[uf.leader(b)];
            uf.merge(a, b);
            cnt[uf.leader(a)] = sum;
            if(deg[a] >= 2 or deg[b] >= 2) check = 0;
            if(check and pre == sum and i != sz - 1) {
                // int val = (i == 0 ? cma - c : max(cma - c, cmp[i - 1]));
                // debug(i, c, val);
                chmin(ans, (i == 0 ? cma - c : max(cma - c, cmp[i - 1])));
            }
        }
        if(i == sz - 1 and i - 1 >= 0) {
            if(uf.size(h[i][0].fr) == si(h[i]) + 1) {
                chmin(ans, cmp[i - 1]);
            }
        }
        for(auto [a, b]: h[i]) {
            deg[a] ++, deg[b] ++;
            cnt[uf.leader(a)] ++;
            if(deg[a] >= 3 or deg[b] >= 3) check = 0;
            ++ pre;
        }
    }
    out(ans);
}

signed main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    // cout << fixed << setprecision(20);
    // INT(t); rep(i, t)solve();
    solve();
    return 0;
}
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