#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define ull unsigned long long
#define pb push_back
#define pll pair<ll, ll>
#define pii pair<ll, int>
#define fi first
#define se second
using namespace std;
const int N = 65;
const int M = 250;
const ll mod = 1e9+7;
const ll base = 75;
const ll inf = 1e16;
int n, lab[N], tong, t, c[N], h[N], k, P[N][8], m, a[N], b[N];
ll ans, d[N];
vector<int> adj[N];
vector<pll> vi;
string s;
bool vis[N];
struct edge
{
int x, y, z;
}e[N];
void add(ll& x, ll y)
{
x += y;
if(x >= mod)x -= mod;
}
void dfs(int u, int p = 0)
{
for(int v: adj[u])
{
if(v == p)continue;
h[v] = h[u]+1;
P[v][0] = u;
for(int j = 1; j < 8; j ++)P[v][j] = P[P[v][j-1]][j-1];
dfs(v, u);
}
}
int lca(int u, int v)
{
if(h[u] < h[v])swap(u, v);
int log = log2(h[u]);
for(int i = log; i >= 0; i --)if(h[u] >= h[v]+(1<<i))u = P[u][i];
if(u == v)return u;
for(int i = log; i >= 0; i --)
{
if(P[u][i] && P[u][i] != P[v][i])
{
u = P[u][i];
v = P[v][i];
}
}
return P[u][0];
}
void cal(int u, int p = 0)
{
bool ok = false;
for(int v: adj[u])
{
if(v == p)continue;
cal(v, u);
c[u] += c[v];
ok |= (c[v] > 0);
}
if(c[u] == 0)
{
if(u > 1)++tong;
if(ok)++tong;
}
}
void sol()
{
cin >> n >> m >> k;
for(int i = 1; i < n; i ++)
{
int x, y;
cin >> x >> y;
adj[x].pb(y);
adj[y].pb(x);
}
d[0] = 1;
for(int i = 1; i < n; i ++)d[i] = 1ll * d[i-1] * k % mod;
dfs(1);
for(int i = 0; i < m; i ++)
{
cin >> e[i].x >> e[i].y;
e[i].z = lca(e[i].x, e[i].y);
}
for(int mask = 0; mask < (1<<m); mask ++)
{
fill_n(c, n+1, 0);
for(int i = 0; i < m; i ++)
{
if(mask >> i & 1)
{
++c[e[i].x];
++c[e[i].y];
c[e[i].z] -= 2;
}
}
tong = 0;
cal(1);
//cout << mask <<" "<< __builtin_popcount(mask) <<" "<<tong << '\n';
if((__builtin_popcount(mask))&1)add(ans, mod-d[tong]);
else add(ans, d[tong]);
}
cout << ans;
}
int main()
{
cin.tie(0);
cout.tie(0);
ios_base::sync_with_stdio(0);
#define task "test"
if(fopen(task".inp", "r"))
{
freopen(task".inp", "r", stdin);
freopen(task".out", "w", stdout);
}
int test = 1;
//cin >> test;
while(test -- > 0)sol();
return 0;
}
/*
1234
21
*/
Compilation message
Main.cpp: In function 'int main()':
Main.cpp:120:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
120 | freopen(task".inp", "r", stdin);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:121:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
121 | freopen(task".out", "w", stdout);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
204 KB |
Output is correct |
2 |
Correct |
1 ms |
204 KB |
Output is correct |
3 |
Correct |
1 ms |
204 KB |
Output is correct |
4 |
Correct |
0 ms |
204 KB |
Output is correct |
5 |
Correct |
1 ms |
204 KB |
Output is correct |
6 |
Correct |
0 ms |
204 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
0 ms |
204 KB |
Output is correct |
2 |
Correct |
0 ms |
204 KB |
Output is correct |
3 |
Correct |
0 ms |
204 KB |
Output is correct |
4 |
Correct |
1 ms |
204 KB |
Output is correct |
5 |
Correct |
0 ms |
204 KB |
Output is correct |
6 |
Correct |
0 ms |
204 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
204 KB |
Output is correct |
2 |
Correct |
1 ms |
204 KB |
Output is correct |
3 |
Correct |
1 ms |
204 KB |
Output is correct |
4 |
Correct |
1 ms |
204 KB |
Output is correct |
5 |
Correct |
3 ms |
332 KB |
Output is correct |
6 |
Correct |
0 ms |
204 KB |
Output is correct |
7 |
Correct |
1 ms |
204 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
204 KB |
Output is correct |
2 |
Incorrect |
0 ms |
204 KB |
Output isn't correct |
3 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
204 KB |
Output is correct |
2 |
Correct |
1 ms |
204 KB |
Output is correct |
3 |
Correct |
1 ms |
204 KB |
Output is correct |
4 |
Correct |
0 ms |
204 KB |
Output is correct |
5 |
Correct |
1 ms |
204 KB |
Output is correct |
6 |
Correct |
0 ms |
204 KB |
Output is correct |
7 |
Correct |
0 ms |
204 KB |
Output is correct |
8 |
Correct |
0 ms |
204 KB |
Output is correct |
9 |
Correct |
0 ms |
204 KB |
Output is correct |
10 |
Correct |
1 ms |
204 KB |
Output is correct |
11 |
Correct |
0 ms |
204 KB |
Output is correct |
12 |
Correct |
0 ms |
204 KB |
Output is correct |
13 |
Correct |
1 ms |
204 KB |
Output is correct |
14 |
Correct |
1 ms |
204 KB |
Output is correct |
15 |
Correct |
1 ms |
204 KB |
Output is correct |
16 |
Correct |
1 ms |
204 KB |
Output is correct |
17 |
Correct |
3 ms |
332 KB |
Output is correct |
18 |
Correct |
0 ms |
204 KB |
Output is correct |
19 |
Correct |
1 ms |
204 KB |
Output is correct |
20 |
Correct |
1 ms |
204 KB |
Output is correct |
21 |
Incorrect |
0 ms |
204 KB |
Output isn't correct |
22 |
Halted |
0 ms |
0 KB |
- |