結果

問題 No.827 総神童数
ユーザー はまやんはまやん
提出日時 2019-05-05 10:08:57
言語 C++14
(gcc 9.3.0)
結果
AC  
実行時間 165 ms / 2,000 ms
コード長 4,193 Byte
コンパイル時間 1,477 ms
使用メモリ 24,056 KB
最終ジャッジ日時 2020-05-04 14:47:39

テストケース

テストケース表示
入力 結果 実行時間
使用メモリ
testcase_00 AC 13 ms
9,272 KB
testcase_01 AC 13 ms
9,272 KB
testcase_02 AC 13 ms
9,276 KB
testcase_03 AC 13 ms
9,272 KB
testcase_04 AC 13 ms
9,272 KB
testcase_05 AC 12 ms
9,272 KB
testcase_06 AC 13 ms
9,272 KB
testcase_07 AC 13 ms
9,276 KB
testcase_08 AC 13 ms
9,276 KB
testcase_09 AC 114 ms
24,056 KB
testcase_10 AC 40 ms
13,760 KB
testcase_11 AC 14 ms
9,536 KB
testcase_12 AC 24 ms
11,652 KB
testcase_13 AC 94 ms
21,420 KB
testcase_14 AC 15 ms
9,804 KB
testcase_15 AC 42 ms
14,028 KB
testcase_16 AC 94 ms
18,512 KB
testcase_17 AC 116 ms
20,624 KB
testcase_18 AC 51 ms
15,084 KB
testcase_19 AC 165 ms
15,344 KB
testcase_20 AC 112 ms
13,764 KB
testcase_21 AC 73 ms
12,704 KB
testcase_22 AC 127 ms
14,288 KB
testcase_23 AC 14 ms
9,272 KB
testcase_24 AC 148 ms
14,816 KB
testcase_25 AC 105 ms
13,500 KB
testcase_26 AC 139 ms
14,820 KB
testcase_27 AC 85 ms
12,968 KB
testcase_28 AC 81 ms
12,964 KB
testcase_29 AC 62 ms
12,172 KB
testcase_30 AC 23 ms
10,068 KB
testcase_31 AC 46 ms
11,648 KB
testcase_32 AC 47 ms
11,384 KB
testcase_33 AC 152 ms
15,348 KB
testcase_34 AC 137 ms
14,820 KB
testcase_35 AC 56 ms
11,648 KB
testcase_36 AC 74 ms
12,444 KB
testcase_37 AC 95 ms
13,500 KB
testcase_38 AC 141 ms
15,080 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 #
#include<bits/stdc++.h>
#define rep(i,a,b) for(int i=a;i<b;i++)
#define rrep(i,a,b) for(int i=a;i>=b;i--)
#define fore(i,a) for(auto &i:a)
#define all(x) (x).begin(),(x).end()
//#pragma GCC optimize ("-O3")
using namespace std; void _main(); int main() { cin.tie(0); ios::sync_with_stdio(false); _main(); }
typedef long long ll; const int inf = INT_MAX / 2; const ll infl = 1LL << 60;
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a = b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a = b; return 1; } return 0; }
//---------------------------------------------------------------------------------------------------
template<int MOD> struct ModInt {
    static const int Mod = MOD; unsigned x; ModInt() : x(0) { }
    ModInt(signed sig) { x = sig < 0 ? sig % MOD + MOD : sig % MOD; }
    ModInt(signed long long sig) { x = sig < 0 ? sig % MOD + MOD : sig % MOD; }
    int get() const { return (int)x; }
    ModInt &operator+=(ModInt that) { if ((x += that.x) >= MOD) x -= MOD; return *this; }
    ModInt &operator-=(ModInt that) { if ((x += MOD - that.x) >= MOD) x -= MOD; return *this; }
    ModInt &operator*=(ModInt that) { x = (unsigned long long)x * that.x % MOD; return *this; }
    ModInt &operator/=(ModInt that) { return *this *= that.inverse(); }
    ModInt operator+(ModInt that) const { return ModInt(*this) += that; }
    ModInt operator-(ModInt that) const { return ModInt(*this) -= that; }
    ModInt operator*(ModInt that) const { return ModInt(*this) *= that; }
    ModInt operator/(ModInt that) const { return ModInt(*this) /= that; }
    ModInt inverse() const { long long a = x, b = MOD, u = 1, v = 0;
        while (b) { long long t = a / b; a -= t * b; std::swap(a, b); u -= t * v; std::swap(u, v); }
        return ModInt(u); }
    bool operator==(ModInt that) const { return x == that.x; }
    bool operator!=(ModInt that) const { return x != that.x; }
    ModInt operator-() const { ModInt t; t.x = x == 0 ? 0 : Mod - x; return t; }
};
template<int MOD> ostream& operator<<(ostream& st, const ModInt<MOD> a) { st << a.get(); return st; };
template<int MOD> ModInt<MOD> operator^(ModInt<MOD> a, unsigned long long k) {
    ModInt<MOD> r = 1; while (k) { if (k & 1) r *= a; a *= a; k >>= 1; } return r; }
template<typename T, int FAC_MAX> struct Comb { vector<T> fac, ifac;
    Comb(){fac.resize(FAC_MAX,1);ifac.resize(FAC_MAX,1);rep(i,1,FAC_MAX)fac[i]=fac[i-1]*i;
        ifac[FAC_MAX-1]=T(1)/fac[FAC_MAX-1];rrep(i,FAC_MAX-2,1)ifac[i]=ifac[i+1]*T(i+1);}
    T aPb(int a, int b) { if (b < 0 || a < b) return T(0); return fac[a] * ifac[a - b]; }
    T aCb(int a, int b) { if (b < 0 || a < b) return T(0); return fac[a] * ifac[a - b] * ifac[b]; }
    T nHk(int n, int k) { if (n == 0 && k == 0) return T(1); if (n <= 0 || k < 0) return 0;
        return aCb(n + k - 1, k); } // nHk = (n+k-1)Ck : n is separator
    T pairCombination(int n) {if(n%2==1)return T(0);return fac[n]*ifac[n/2]/(T(2)^(n/2));}
    // combination of paris for n
}; 
typedef ModInt<1000000007> mint;
/*---------------------------------------------------------------------------------------------------
            ∧_∧  
      ∧_∧  (´<_` )  Welcome to My Coding Space!
     ( ´_ゝ`) /  ⌒i     
    /   \     | |     
    /   / ̄ ̄ ̄ ̄/  |  
  __(__ニつ/     _/ .| .|____  
     \/____/ (u ⊃  
---------------------------------------------------------------------------------------------------*/






int N;
vector<int> E[201010];
Comb<mint, 401010> com;
//---------------------------------------------------------------------------------------------------
mint ans = 0;
void dfs(int cu, int pa = -1, int dpt = 1) {
	ans += com.aCb(N, dpt) * com.fac[dpt - 1] * com.fac[N - dpt];
	fore(to, E[cu]) if (to != pa) dfs(to, cu, dpt + 1);
}
//---------------------------------------------------------------------------------------------------
void _main() {
	cin >> N;
	rep(i, 0, N - 1) {
		int a, b; cin >> a >> b;
		E[a].push_back(b);
		E[b].push_back(a);
	}

	dfs(1);
	cout << ans << endl;
}
0