Submission #11375289
Source Code Expand
#include <iostream>
#include <algorithm>
#include <complex>
#include <utility>
#include <vector>
#include <string>
#include <queue>
#include <tuple>
#include <cmath>
#include <bitset>
#include <cctype>
#include <set>
#include <numeric>
#include <functional>
#define _overload3(_1,_2,_3,name,...) name
#define _rep(i,n) repi(i,0,n)
#define repi(i,a,b) for(ll i=ll(a);i<ll(b);++i)
#define rep(...) _overload3(__VA_ARGS__,repi,_rep,)(__VA_ARGS__)
#define all(x) (x).begin(),(x).end()
#define PRINT(V) cout << V << "\n"
#define SORT(V) sort((V).begin(),(V).end())
#define RSORT(V) sort((V).rbegin(), (V).rend())
using namespace std;
using ll = long long;
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; }
inline bool Yes(bool condition){ if(condition) PRINT("Yes"); else PRINT("No"); }
template<class itr> void cins(itr first,itr last){
for (auto i = first;i != last;i++){
cin >> (*i);
}
}
template<class itr> void array_output(itr start,itr goal){
string ans = "",k = " ";
for (auto i = start;i != goal;i++) ans += to_string(*i)+k;
if (!ans.empty()) ans.pop_back();
PRINT(ans);
}
ll gcd(ll a, ll b) {
return a ? gcd(b%a,a) : b;
}
const ll INF = 1e17;
const ll MOD = 1000000007;
typedef pair<ll,ll> P;
const ll MAX = 1005;
ll n;
vector<P> to;
vector<ll> done(10005);
ll fac[MAX], finv[MAX], inv[MAX];
void COMinit() {
fac[0] = fac[1] = 1;
finv[0] = finv[1] = 1;
inv[1] = 1;
for (ll i = 2; i < MAX; i++){
fac[i] = fac[i - 1] * i % MOD;
inv[i] = MOD - inv[MOD%i] * (MOD / i) % MOD;
finv[i] = finv[i - 1] * inv[i] % MOD;
}
}
ll COM(ll n, ll k){
if (n < k) return 0;
if (n < 0 || k < 0) return 0;
return fac[n] * (finv[k] * finv[n - k] % MOD) % MOD;
}
P dfs(ll node,vector<vector<ll>> g){
done[node] = true;
ll size = 0,p = 1;
vector<ll> siz;
for(ll v:g[node]){
if (done[v]) continue;
ll s,q;
tie(s,q) = dfs(v,g);
size += s;
siz.push_back(s);
p *= q;
p %= MOD;
}
ll k = size+1;
for(ll i:siz){
p *= COM(size,i);
p %= MOD;
size -= i;
}
return P(k,p);
}
int main(){
cin.tie(0);
ios::sync_with_stdio(false);
cin >> n;
ll a,b;
COMinit();
rep(i,n-1){
cin >> a >> b;
--a;
--b;
to.push_back(P(a,b));
}
ll ans = 0;
rep(i,n-1){
rep(i,n) done[i] = false;
tie(a,b) = to[i];
vector<vector<ll>> g(n);
ll x,y;
rep(j,n-1){
if (i == j) continue;
tie(x,y) = to[j];
if (x == b) x = a;
if (y == b) y = a;
g[x].push_back(y);
g[y].push_back(x);
}
ans += dfs(a,g).second;
ans %= MOD;
}
PRINT(ans);
}
Submission Info
Submission Time |
|
Task |
N - 木 |
User |
karudano |
Language |
C++14 (GCC 5.4.1) |
Score |
0 |
Code Size |
3033 Byte |
Status |
TLE |
Exec Time |
2107 ms |
Memory |
54656 KB |
Judge Result
Set Name |
All |
Score / Max Score |
0 / 5 |
Status |
|
Set Name |
Test Cases |
All |
00, 01, 02, 03, 04, 05, 06, 90, 91 |
Case Name |
Status |
Exec Time |
Memory |
00 |
TLE |
2107 ms |
54656 KB |
01 |
TLE |
2103 ms |
512 KB |
02 |
TLE |
2103 ms |
1792 KB |
03 |
TLE |
2103 ms |
1664 KB |
04 |
TLE |
2103 ms |
1792 KB |
05 |
TLE |
2103 ms |
1760 KB |
06 |
TLE |
2103 ms |
1920 KB |
90 |
AC |
1 ms |
384 KB |
91 |
AC |
1 ms |
384 KB |