#include <bits/stdc++.h>
#define ll long long
#define vc vector
using namespace std;
struct dsu{
ll n, cc;
vc<ll> d;
dsu(ll n_):n(n_){d.resize(n); for(ll i=0;i<n;++i) d[i]=i;cc=n;}
ll fnd(ll u){assert(u>=0 && u<n);return (u==d[u])?u:d[u]=fnd(d[u]);}
void join(ll a, ll b){assert(a>=0 && a<n);assert(b>=0 && b<n);ll pa=fnd(a), pb=fnd(b);if(pa!=pb) d[pa]=pb, --cc;}
};
const ll mod=1e9+7;
ll fpow(ll b, ll e){ll ret=1;for(;e;e/=2, b=b*b%mod, ret%=mod)if(e&1)ret*=b;return ret;}
int main() {
ll n, m, k;cin >> n >> m >> k;
vc<vc<pair<ll, ll>>> edg(n+1);
for(ll i=0;i<n-1;++i){
ll a, b;cin >> a >> b;
edg[a].emplace_back(b, i);
edg[b].emplace_back(a, i);
}
vc<ll> s(m), e(m);
for(ll i=0;i<m;++i) cin >> s[i] >> e[i];
vc<vc<ll>> ued(m);
for(ll i=0;i<m;++i){
function<ll (ll, ll)> dfs=[&](ll u, ll p){
if(u==e[i]) return 1LL;
for(auto v: edg[u]) if(v.first!=p){
if(dfs(v.first, u)){ ued[i].push_back(v.second); return 1LL;}
}
return 0LL;
};
dfs(s[i], -1);
//for(auto ed: ued[i]) cout <<ed <<" "; cout << endl;
}
ll ans=0;
for(ll b=0;b<(1<<m);++b){
dsu D(n-1);
for(ll i=0;i<m;++i) if(b&(1<<i)){
for(ll j=0;j+1<ued[i].size();++j) D.join(ued[i][j], ued[i][j+1]);
}
//cout << D.cc<<endl;
ans+=mod+((__builtin_popcountll(b)%2)? -1LL:1LL) * fpow(k, D.cc); ans%=mod;
}
cout << ans << endl;
}
Compilation message
Main.cpp: In function 'int main()':
Main.cpp:43:27: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
43 | for(ll j=0;j+1<ued[i].size();++j) D.join(ued[i][j], ued[i][j+1]);
| ~~~^~~~~~~~~~~~~~
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
212 KB |
Output is correct |
2 |
Correct |
1 ms |
212 KB |
Output is correct |
3 |
Correct |
0 ms |
212 KB |
Output is correct |
4 |
Correct |
1 ms |
212 KB |
Output is correct |
5 |
Correct |
0 ms |
212 KB |
Output is correct |
6 |
Correct |
0 ms |
212 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
212 KB |
Output is correct |
2 |
Correct |
0 ms |
212 KB |
Output is correct |
3 |
Correct |
1 ms |
300 KB |
Output is correct |
4 |
Correct |
1 ms |
212 KB |
Output is correct |
5 |
Correct |
1 ms |
300 KB |
Output is correct |
6 |
Correct |
1 ms |
212 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
212 KB |
Output is correct |
2 |
Correct |
0 ms |
212 KB |
Output is correct |
3 |
Correct |
1 ms |
220 KB |
Output is correct |
4 |
Correct |
1 ms |
308 KB |
Output is correct |
5 |
Correct |
1 ms |
220 KB |
Output is correct |
6 |
Correct |
1 ms |
216 KB |
Output is correct |
7 |
Correct |
0 ms |
212 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
0 ms |
216 KB |
Output is correct |
2 |
Correct |
1 ms |
216 KB |
Output is correct |
3 |
Correct |
0 ms |
212 KB |
Output is correct |
4 |
Correct |
0 ms |
212 KB |
Output is correct |
5 |
Correct |
2 ms |
216 KB |
Output is correct |
6 |
Correct |
3 ms |
304 KB |
Output is correct |
7 |
Correct |
0 ms |
212 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
212 KB |
Output is correct |
2 |
Correct |
1 ms |
212 KB |
Output is correct |
3 |
Correct |
0 ms |
212 KB |
Output is correct |
4 |
Correct |
1 ms |
212 KB |
Output is correct |
5 |
Correct |
0 ms |
212 KB |
Output is correct |
6 |
Correct |
0 ms |
212 KB |
Output is correct |
7 |
Correct |
1 ms |
212 KB |
Output is correct |
8 |
Correct |
0 ms |
212 KB |
Output is correct |
9 |
Correct |
1 ms |
300 KB |
Output is correct |
10 |
Correct |
1 ms |
212 KB |
Output is correct |
11 |
Correct |
1 ms |
300 KB |
Output is correct |
12 |
Correct |
1 ms |
212 KB |
Output is correct |
13 |
Correct |
1 ms |
212 KB |
Output is correct |
14 |
Correct |
0 ms |
212 KB |
Output is correct |
15 |
Correct |
1 ms |
220 KB |
Output is correct |
16 |
Correct |
1 ms |
308 KB |
Output is correct |
17 |
Correct |
1 ms |
220 KB |
Output is correct |
18 |
Correct |
1 ms |
216 KB |
Output is correct |
19 |
Correct |
0 ms |
212 KB |
Output is correct |
20 |
Correct |
0 ms |
216 KB |
Output is correct |
21 |
Correct |
1 ms |
216 KB |
Output is correct |
22 |
Correct |
0 ms |
212 KB |
Output is correct |
23 |
Correct |
0 ms |
212 KB |
Output is correct |
24 |
Correct |
2 ms |
216 KB |
Output is correct |
25 |
Correct |
3 ms |
304 KB |
Output is correct |
26 |
Correct |
0 ms |
212 KB |
Output is correct |
27 |
Correct |
9 ms |
304 KB |
Output is correct |
28 |
Correct |
1 ms |
212 KB |
Output is correct |
29 |
Correct |
1 ms |
300 KB |
Output is correct |
30 |
Correct |
10 ms |
308 KB |
Output is correct |
31 |
Correct |
3 ms |
300 KB |
Output is correct |
32 |
Correct |
1 ms |
212 KB |
Output is correct |
33 |
Correct |
1 ms |
212 KB |
Output is correct |
34 |
Correct |
1 ms |
212 KB |
Output is correct |
35 |
Correct |
6 ms |
212 KB |
Output is correct |
36 |
Correct |
29 ms |
212 KB |
Output is correct |
37 |
Correct |
12 ms |
212 KB |
Output is correct |