結果

問題 No.1507 Road Blocked
ユーザー rokahikou1rokahikou1
提出日時 2021-05-18 20:59:40
言語 C++14
(gcc 12.3.0 + boost 1.83.0)
結果
AC  
実行時間 50 ms / 2,000 ms
コード長 6,630 bytes
コンパイル時間 2,256 ms
コンパイル使用メモリ 174,684 KB
実行使用メモリ 13,424 KB
最終ジャッジ日時 2023-07-30 06:27:24
合計ジャッジ時間 5,608 ms
ジャッジサーバーID
(参考情報)
judge11 / judge15
このコードへのチャレンジ(β)

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 AC 1 ms
4,356 KB
testcase_01 AC 1 ms
4,380 KB
testcase_02 AC 2 ms
4,380 KB
testcase_03 AC 35 ms
13,424 KB
testcase_04 AC 45 ms
9,892 KB
testcase_05 AC 45 ms
9,892 KB
testcase_06 AC 43 ms
9,760 KB
testcase_07 AC 44 ms
9,732 KB
testcase_08 AC 48 ms
9,856 KB
testcase_09 AC 49 ms
9,684 KB
testcase_10 AC 43 ms
9,616 KB
testcase_11 AC 47 ms
9,728 KB
testcase_12 AC 44 ms
9,620 KB
testcase_13 AC 49 ms
9,612 KB
testcase_14 AC 43 ms
9,728 KB
testcase_15 AC 47 ms
9,760 KB
testcase_16 AC 44 ms
9,624 KB
testcase_17 AC 46 ms
9,692 KB
testcase_18 AC 46 ms
9,676 KB
testcase_19 AC 45 ms
9,684 KB
testcase_20 AC 48 ms
9,880 KB
testcase_21 AC 47 ms
9,604 KB
testcase_22 AC 47 ms
9,620 KB
testcase_23 AC 48 ms
9,752 KB
testcase_24 AC 47 ms
9,688 KB
testcase_25 AC 48 ms
9,692 KB
testcase_26 AC 47 ms
9,760 KB
testcase_27 AC 47 ms
9,612 KB
testcase_28 AC 47 ms
9,612 KB
testcase_29 AC 48 ms
9,736 KB
testcase_30 AC 44 ms
9,624 KB
testcase_31 AC 49 ms
9,740 KB
testcase_32 AC 50 ms
9,664 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 #

#pragma region Macros
#include <bits/stdc++.h>
#define rep(i, n) for(int(i) = 0; (i) < (n); (i)++)
#define FOR(i, m, n) for(int(i) = (m); (i) < (n); (i)++)
#define ALL(v) (v).begin(), (v).end()
#define LLA(v) (v).rbegin(), (v).rend()
#define SZ(v) (int)(v).size()
#define INT(...)                                                               \
    int __VA_ARGS__;                                                           \
    read(__VA_ARGS__)
#define LL(...)                                                                \
    ll __VA_ARGS__;                                                            \
    read(__VA_ARGS__)
#define DOUBLE(...)                                                            \
    double __VA_ARGS__;                                                        \
    read(__VA_ARGS__)
#define CHAR(...)                                                              \
    char __VA_ARGS__;                                                          \
    read(__VA_ARGS__)
#define STRING(...)                                                            \
    string __VA_ARGS__;                                                        \
    read(__VA_ARGS__)
#define VEC(type, name, size)                                                  \
    vector<type> name(size);                                                   \
    read(name)
#define VEC2(type, name, height, width)                                        \
    vector<vector<type>> name(height, vector<type>(width));                    \
    read(name)
using namespace std;
using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using Graph = vector<vector<int>>;
template <typename T> struct edge {
    int from, to;
    T cost;
    edge(int f, int t, T c) : from(f), to(t), cost(c) {}
};
template <typename T> using WGraph = vector<vector<edge<T>>>;
const int INF = 1 << 30;
const ll LINF = 1LL << 60;
const int MOD = 998244353;
const char newl = '\n';
template <class T> inline vector<T> make_vec(size_t a, T val) {
    return vector<T>(a, val);
}
template <class... Ts> inline auto make_vec(size_t a, Ts... ts) {
    return vector<decltype(make_vec(ts...))>(a, make_vec(ts...));
}
void read() {}
template <class T> inline void read(T &a) { cin >> a; }
template <class T, class S> inline void read(pair<T, S> &p) {
    read(p.first), read(p.second);
}
template <class T> inline void read(vector<T> &v) {
    for(auto &&a : v)
        read(a);
}
template <class Head, class... Tail>
inline void read(Head &head, Tail &...tail) {
    read(head), read(tail...);
}
template <class T> void write(const T &a) { cout << a << '\n'; }
template <class T> void write(const vector<T> &a) {
    for(int i = 0; i < a.size(); i++)
        cout << a[i] << (i + 1 == a.size() ? '\n' : ' ');
}
template <class Head, class... Tail>
void write(const Head &head, const Tail &...tail) {
    cout << head << ' ';
    write(tail...);
}
template <class T> void writel(const T &a) { cout << a << '\n'; }
template <class T> void writel(const vector<T> &a) {
    for(int i = 0; i < a.size(); i++)
        cout << a[i] << '\n';
}
template <class Head, class... Tail>
void writel(const Head &head, const Tail &...tail) {
    cout << head << '\n';
    write(tail...);
}
template <class T> auto sum(const vector<T> &a) {
    return accumulate(ALL(a), T(0));
}
template <class T> auto min(const vector<T> &a) { return *min_element(ALL(a)); }
template <class T> auto max(const vector<T> &a) { return *max_element(ALL(a)); }
template <class T> inline void chmax(T &a, T b) { (a < b ? a = b : a); }
template <class T> inline void chmin(T &a, T b) { (a > b ? a = b : a); }
struct IO {
    IO() {
        ios::sync_with_stdio(false);
        cin.tie(nullptr);
        cout << fixed << setprecision(10);
    }
} io;
#pragma endregion

template <uint_fast64_t MOD> class ModInt {
    using u64 = uint_fast64_t;

  public:
    u64 val;

    ModInt(const u64 x = 0) : val((x + MOD) % MOD) {}
    constexpr u64 &value() { return val; }
    constexpr ModInt operator-() { return val ? MOD - val : 0; }
    constexpr ModInt operator+(const ModInt &rhs) const {
        return ModInt(*this) += rhs;
    }
    constexpr ModInt operator-(const ModInt &rhs) const {
        return ModInt(*this) -= rhs;
    }
    constexpr ModInt operator*(const ModInt &rhs) const {
        return ModInt(*this) *= rhs;
    }
    constexpr ModInt operator/(const ModInt &rhs) const {
        return ModInt(*this) /= rhs;
    }
    constexpr ModInt &operator+=(const ModInt &rhs) {
        val += rhs.val;
        if(val >= MOD) {
            val -= MOD;
        }
        return *this;
    }
    constexpr ModInt &operator-=(const ModInt &rhs) {
        if(val < rhs.val) {
            val += MOD;
        }
        val -= rhs.val;
        return *this;
    }
    constexpr ModInt &operator*=(const ModInt &rhs) {
        val = val * rhs.val % MOD;
        return *this;
    }

    constexpr ModInt &operator/=(const ModInt &rhs) {
        *this *= rhs.inv();
        return *this;
    }

    constexpr bool operator==(const ModInt &rhs) {
        return this->val == rhs.val;
    }
    constexpr bool operator!=(const ModInt &rhs) {
        return this->val != rhs.val;
    }
    friend constexpr ostream &operator<<(ostream &os, const ModInt<MOD> &x) {
        return os << x.val;
    }
    friend constexpr istream &operator>>(istream &is, ModInt<MOD> &x) {
        return is >> x.val;
    }

    constexpr ModInt inv() const { return ModInt(*this).pow(MOD - 2); }

    constexpr ModInt pow(ll e) const {
        u64 x = 1, p = val;
        while(e > 0) {
            if(e % 2 == 0) {
                p = (p * p) % MOD;
                e /= 2;
            } else {
                x = (x * p) % MOD;
                e--;
            }
        }
        return ModInt(x);
    }
};

using mint = ModInt<MOD>;

int main() {
    INT(n);
    Graph g(n);
    vector<pii> edges;
    rep(i, n - 1) {
        INT(a, b);
        a--, b--;
        g[a].push_back(b);
        g[b].push_back(a);
        edges.push_back({a, b});
    }
    vector<int> sz(n, -1);
    auto dfs = [&](auto &&dfs, int v, int p) -> int {
        if(p != -1 && g[v].size() == 1) {
            return sz[v] = 1;
        }
        int ret = 1;
        for(auto nv : g[v]) {
            if(nv == p)
                continue;
            ret += dfs(dfs, nv, v);
        }
        return sz[v] = ret;
    };
    dfs(dfs, 0, -1);
    mint res = 0;
    for(auto e : edges) {
        int k = min(sz[e.first], sz[e.second]);
        res += mint(k) * (n - k);
    }
    write(mint(1) - res * 2 / (mint(n) * (n - 1) * (n - 1)));
}
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