結果

問題 No.758 VVVVV
コンテスト
ユーザー firiexp
提出日時 2018-12-06 00:31:23
言語 C++14
(gcc 13.3.0 + boost 1.87.0)
結果
CE  
(最新)
AC  
(最初)
実行時間 -
コード長 2,409 bytes
コンパイル時間 670 ms
コンパイル使用メモリ 80,464 KB
最終ジャッジ日時 2025-03-14 22:41:48
合計ジャッジ時間 1,694 ms
ジャッジサーバーID
（参考情報） 		judge3 / judge2
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コンパイルエラー時のメッセージ・ソースコードは、提出者また管理者しか表示できないようにしております。（リジャッジ後のコンパイルエラーは公開されます）
ただし、clay言語の場合は開発者のデバッグのため、公開されます。

コンパイルメッセージ
main.cpp: In function ‘T pow_(T, T, T)’:
main.cpp:19:5: error: ‘uint64_t’ was not declared in this scope
   19 |     uint64_t u = 1, xx = x;
      |     ^~~~~~~~
main.cpp:8:1: note: ‘uint64_t’ is defined in header ‘<cstdint>’; did you forget to ‘#include <cstdint>’?
    7 | #include <queue>
  +++ |+#include <cstdint>
    8 | 
main.cpp:21:18: error: ‘u’ was not declared in this scope
   21 |         if (n&1) u = u * xx % M;
      |                  ^
main.cpp:21:26: error: ‘xx’ was not declared in this scope; did you mean ‘x’?
   21 |         if (n&1) u = u * xx % M;
      |                          ^~
      |                          x
main.cpp:22:9: error: ‘xx’ was not declared in this scope; did you mean ‘x’?
   22 |         xx = xx * xx % M;
      |         ^~
      |         x
main.cpp:25:27: error: ‘u’ was not declared in this scope
   25 |     return static_cast<T>(u);
      |                           ^
main.cpp: At global scope:
main.cpp:30:12: error: ‘uint64_t’ was not declared in this scope
   30 |     vector<uint64_t> facts, factinv;
      |            ^~~~~~~~
main.cpp:30:12: note: ‘uint64_t’ is defined in header ‘<cstdint>’; did you forget to ‘#include <cstdint>’?
main.cpp:30:20: error: template argument 1 is invalid
   30 |     vector<uint64_t> facts, factinv;
      |                    ^
main.cpp:30:20: error: template argument 2 is invalid
main.cpp: In constructor ‘Factorial<T>::Factorial(int, T)’:
main.cpp:34:14: error: invalid types ‘int[int]’ for array subscript
   34 |         facts[0] = 1;
      |              ^
main.cpp:35:44: error: invalid types ‘int[int]’ for array subscript
   35 |         for (int i = 1; i < n+1; ++i) facts[i] = facts[i-1]*i % mod;
      |                                            ^
main.cpp:35:55: error: invalid types ‘int[int]’ for array subscript
   35 |         for (int i = 1; i < n+1; ++i) facts[i] = facts[i-1]*i % mod;
      |

ソースコード

diff # 

#include <limits>
#include <iostream>
#include <algorithm>
#include <vector>
#include <iomanip>
#include <map>
#include <queue>

static const int MOD = 1000000007;
using ll = long long;
using u32 = unsigned;
using namespace std;

template<class T>
constexpr T INF = ::numeric_limits<T>::max() / 32 * 15 + 208;

template <class T>
T pow_ (T x, T n, T M){
    uint64_t u = 1, xx = x;
    while (n > 0){
        if (n&1) u = u * xx % M;
        xx = xx * xx % M;
        n >>= 1;
    }
    return static_cast<T>(u);
};

template <class T> class Factorial {
    T mod;
    vector<uint64_t> facts, factinv;

public:
    Factorial(int n, T mod) : facts(static_cast<u32>(n+1)), factinv(static_cast<u32>(n+1)), mod(mod) {
        facts[0] = 1;
        for (int i = 1; i < n+1; ++i) facts[i] = facts[i-1]*i % mod;
        factinv[n] = pow_(facts[n], static_cast<uint64_t>(mod - 2), static_cast<uint64_t>(mod));
        for (int i = n-1; i >= 0; --i) factinv[i] = factinv[i+1] * (i+1) % mod;
    }

    T fact(int k) const {
        return static_cast<T>(facts[k]);
    }

    T operator[](const int &k) const {
        return static_cast<T>(facts[k]);
    }

    T C(int p, int q) const {
        if(q < 0 || p < q) return 0;
        return static_cast<T>(facts[p]*  factinv[q] % mod * factinv[p-q] % mod);
    }

    T P(int p, int q) const {
        if(q < 0 || p < q) return 0;
        return static_cast<T>((facts[p] * factinv[p-q]) % mod);
    }

    T H(int p, int q) const {
        if(p < 0 || q < 0) return 0;
        return static_cast<T>(q == 0 ? 1 : C(p+q-1, q));
    }
};

template<typename T>
T extgcd(T a, T b, T &x ,T &y){
    for (T u = y = 1, v = x = 0; a; ) {
        ll q = b/a;
        swap(x -= q*u, u);
        swap(y -= q*v, v);
        swap(b -= q*a, a);
    }
    return b;
}

template<typename T>
T mod_inv(T x, T m){
    T s, t;
    extgcd(x, m, s, t);
    return (m+s)% m;
}



int main() {
    int n;
    cin >> n;
    if(n == 1) {
        cout << 1 << "\n";
        return 0;
    }
    vector<vector<int>> child(n);
    for (int i = 0; i < n-1; ++i) {
        int a, b;
        cin >> a >> b;
        if(a > b) swap(a, b);

        child[a-1].emplace_back(b-1);
    }
    int k = 0;
    for (int i = 0; i < n; ++i) {
        if(child[i].empty()) k++;
    }

    Factorial<ll> f(n, MOD);

    cout << ((f.C(n-2, k-1) * f.C(n-1, k-1)) % MOD)*mod_inv(k, MOD) % MOD << "\n";
    return 0;
}
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