結果
問題 | No.758 VVVVV |
ユーザー |
|
提出日時 | 2018-12-19 08:52:39 |
言語 | C++14 (gcc 13.3.0 + boost 1.87.0) |
結果 |
AC
|
実行時間 | 51 ms / 2,000 ms |
コード長 | 3,393 bytes |
コンパイル時間 | 1,815 ms |
コンパイル使用メモリ | 169,952 KB |
実行使用メモリ | 5,248 KB |
最終ジャッジ日時 | 2024-10-14 01:50:20 |
合計ジャッジ時間 | 3,780 ms |
ジャッジサーバーID (参考情報) |
judge3 / judge4 |
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ファイルパターン | 結果 |
---|---|
sample | AC * 3 |
other | AC * 23 |
ソースコード
#define _USE_MATH_DEFINES#include "bits/stdc++.h"using namespace std;#define FOR(i,j,k) for(int (i)=(j);(i)<(int)(k);++(i))#define rep(i,j) FOR(i,0,j)#define each(x,y) for(auto &(x):(y))#define mp make_pair#define MT make_tuple#define all(x) (x).begin(),(x).end()#define debug(x) cout<<#x<<": "<<(x)<<endl#define smax(x,y) (x)=max((x),(y))#define smin(x,y) (x)=min((x),(y))#define MEM(x,y) memset((x),(y),sizeof (x))#define sz(x) (int)(x).size()#define RT returnusing ll = long long;using pii = pair<int, int>;using vi = vector<int>;using vll = vector<ll>;template<int MOD>class ModInt {public:ModInt() :value(0) {}ModInt(long long val) :value((int)(val<0 ? MOD + val % MOD : val % MOD)) { }ModInt& operator+=(ModInt that) {value = value + that.value;if (value >= MOD)value -= MOD;return *this;}ModInt& operator-=(ModInt that) {value -= that.value;if (value<0)value += MOD;return *this;}ModInt& operator*=(ModInt that) {value = (int)((long long)value * that.value % 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 pow(long long k) const {ModInt n = *this, res = 1;while (k) {if (k & 1)res *= n;n *= n;k >>= 1;}return res;}ModInt inverse() const {long long a = value, b = MOD, u = 1, v = 0;while (b) {long long t = a / b;a -= t * b;swap(a, b);u -= t * v;swap(u, v);}return ModInt(u);}int toi() const { return value; }private:int value;};typedef ModInt<1000000007> mint;ostream& operator<<(ostream& os, const mint& x) {os << x.toi();return os;}namespace comb {const int N = 100005;mint fact[N];mint rev[N];void init() {fact[0] = 1;for (int i = 1; i < N; ++i)fact[i] = fact[i - 1] * i;for (int i = 0; i < N; ++i)rev[i] = fact[i].inverse();}mint C(int n, int r) {if (n < r)return 0;return fact[n] * rev[r] * rev[n - r];}mint H(int n, int r) {return C(n + r - 1, r);}mint P(int n, int r) {assert(n >= r);return fact[n] * rev[n - r];}mint catalan(int n) {return fact[2 * n] * rev[n + 1] * rev[n];}}mint narayana(int m, int l) {return comb::C(m, l - 1)*comb::C(m - 1, l - 1) / l;}void solve() {comb::init();int N;cin >> N;vi deg(N);rep(i, N-1) {int u, v;cin >> u >> v;deg[u - 1]++;deg[v - 1]++;}if (N == 1) {cout << 1 << endl;return;}int leaves = 0;FOR(i, 1, N) {if (deg[i] == 1)leaves++;}cout << narayana(N - 1, leaves) << endl;}int main() {ios::sync_with_stdio(false);cin.tie(0);cout << fixed << setprecision(15);solve();return 0;}