#include <bits/stdc++.h>
using namespace std;
const long long mod = 1e9 + 7;
int n, m, k;
long long power[75];
bitset<75> edge[20];
vector<pair<int, int>> adj[75];
vector<int> graph[75];
int save[75], depth[75], par[75];
bool visited[75];
void pre_dfs(int u, int pre) {
for (auto it: adj[u]) {
int v = it.first, id = it.second;
if (v == pre) continue;
save[v] = id;
depth[v] = depth[u] + 1;
par[v] = u;
pre_dfs(v, u);
}
}
void dfs(int u, int mask) {
visited[u] = true;
for (auto v: graph[u]) {
if (!visited[v] && (mask & (1 << (v - 1)))) dfs(v, mask);
}
}
int main() {
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
cin >> n >> m >> k;
for (int i = 1; i < n; i++) {
int u, v;
cin >> u >> v;
adj[u].push_back({v, i});
adj[v].push_back({u, i});
}
pre_dfs(1, 1);
for (int i = 1; i <= m; i++) {
int u, v;
cin >> u >> v;
if (depth[u] < depth[v]) swap(u, v);
while (depth[u] != depth[v]) {
edge[i][save[u]] = 1;
u = par[u];
}
while (u != v) {
edge[i][save[u]] = 1;
edge[i][save[v]] = 1;
u = par[u];
v = par[v];
}
}
for (int i = 1; i <= m; i++) {
if (edge[i].count() < 2) {
cout << 0;
return 0;
}
}
for (int i = 1; i <= m; i++) {
for (int j = i + 1; j <= m; j++) {
bitset<75> calc = edge[i] & edge[j];
if (calc.count()) {
graph[i].push_back(j);
graph[j].push_back(i);
//cout << "graph " << i << ' ' << j << '\n';
}
}
}
power[0] = 1;
for (int i = 1; i <= n; i++)
power[i] = (1LL * k * power[i - 1]) % mod;
long long ans = power[n - 1]; //cout << power[n - 1] << '\n';
for (int mask = 1; mask < (1 << m); mask++) {
bitset<75> keep; int com = 0, rem = n - 1;
memset(visited, false, sizeof visited);
for (int i = 1; i <= m; i++) {
if (mask & (1 << (i - 1))) {
keep = keep | edge[i];
if (!visited[i]) {
com++;
dfs(i, mask);
}
}
}
rem = rem - keep.count();
if (__builtin_popcount(mask) % 2 == 1) ans = (ans - power[rem + com] + mod) % mod;
else ans = (ans + power[rem + com]) % mod;
//cout << mask << ' ' << rem << ' ' << com << ' ' << ans << '\n';
}
cout << ans;
return 0;
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
336 KB |
Output is correct |
2 |
Correct |
1 ms |
336 KB |
Output is correct |
3 |
Correct |
1 ms |
336 KB |
Output is correct |
4 |
Correct |
1 ms |
336 KB |
Output is correct |
5 |
Correct |
1 ms |
336 KB |
Output is correct |
6 |
Correct |
1 ms |
336 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
336 KB |
Output is correct |
2 |
Correct |
1 ms |
336 KB |
Output is correct |
3 |
Correct |
1 ms |
336 KB |
Output is correct |
4 |
Correct |
1 ms |
592 KB |
Output is correct |
5 |
Correct |
1 ms |
336 KB |
Output is correct |
6 |
Correct |
1 ms |
336 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
336 KB |
Output is correct |
2 |
Correct |
0 ms |
336 KB |
Output is correct |
3 |
Correct |
1 ms |
336 KB |
Output is correct |
4 |
Correct |
1 ms |
336 KB |
Output is correct |
5 |
Correct |
1 ms |
336 KB |
Output is correct |
6 |
Correct |
1 ms |
508 KB |
Output is correct |
7 |
Correct |
1 ms |
336 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
336 KB |
Output is correct |
2 |
Correct |
1 ms |
336 KB |
Output is correct |
3 |
Correct |
1 ms |
336 KB |
Output is correct |
4 |
Correct |
1 ms |
336 KB |
Output is correct |
5 |
Correct |
3 ms |
336 KB |
Output is correct |
6 |
Correct |
3 ms |
504 KB |
Output is correct |
7 |
Correct |
1 ms |
336 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
336 KB |
Output is correct |
2 |
Correct |
1 ms |
336 KB |
Output is correct |
3 |
Correct |
1 ms |
336 KB |
Output is correct |
4 |
Correct |
1 ms |
336 KB |
Output is correct |
5 |
Correct |
1 ms |
336 KB |
Output is correct |
6 |
Correct |
1 ms |
336 KB |
Output is correct |
7 |
Correct |
1 ms |
336 KB |
Output is correct |
8 |
Correct |
1 ms |
336 KB |
Output is correct |
9 |
Correct |
1 ms |
336 KB |
Output is correct |
10 |
Correct |
1 ms |
592 KB |
Output is correct |
11 |
Correct |
1 ms |
336 KB |
Output is correct |
12 |
Correct |
1 ms |
336 KB |
Output is correct |
13 |
Correct |
1 ms |
336 KB |
Output is correct |
14 |
Correct |
0 ms |
336 KB |
Output is correct |
15 |
Correct |
1 ms |
336 KB |
Output is correct |
16 |
Correct |
1 ms |
336 KB |
Output is correct |
17 |
Correct |
1 ms |
336 KB |
Output is correct |
18 |
Correct |
1 ms |
508 KB |
Output is correct |
19 |
Correct |
1 ms |
336 KB |
Output is correct |
20 |
Correct |
1 ms |
336 KB |
Output is correct |
21 |
Correct |
1 ms |
336 KB |
Output is correct |
22 |
Correct |
1 ms |
336 KB |
Output is correct |
23 |
Correct |
1 ms |
336 KB |
Output is correct |
24 |
Correct |
3 ms |
336 KB |
Output is correct |
25 |
Correct |
3 ms |
504 KB |
Output is correct |
26 |
Correct |
1 ms |
336 KB |
Output is correct |
27 |
Correct |
5 ms |
336 KB |
Output is correct |
28 |
Correct |
1 ms |
336 KB |
Output is correct |
29 |
Correct |
1 ms |
336 KB |
Output is correct |
30 |
Correct |
5 ms |
336 KB |
Output is correct |
31 |
Correct |
2 ms |
336 KB |
Output is correct |
32 |
Correct |
1 ms |
336 KB |
Output is correct |
33 |
Correct |
1 ms |
336 KB |
Output is correct |
34 |
Correct |
1 ms |
336 KB |
Output is correct |
35 |
Correct |
3 ms |
336 KB |
Output is correct |
36 |
Correct |
16 ms |
336 KB |
Output is correct |
37 |
Correct |
7 ms |
336 KB |
Output is correct |