#include <cstdio>
#include <vector>
using namespace std;
const int MAXN = 61;
const int MAXM = 16;
const int MOD = 1000000007;
int n,m,k;
vector<int> graph[MAXN];
int depth[MAXN];
int parent[MAXN];
long long path[MAXM];
int popcount(long long x){
int res=0;
for(;x;x>>=1){
if(x&1) res++;
}
return res;
}
int ADD(long long a, long long b){
return (a+b)%MOD;
}
int SUB(long long a, long long b){
return (a+MOD-b)%MOD;
}
int MUL(long long a, long long b){
return a*b%MOD;
}
int EXP(long long a, long long b){
if(b==0) return 1;
if(b%2==1) return MUL(a, EXP(a, b-1));
else return EXP(MUL(a, a), b/2);
}
void dfs(int node, int p=-1, int d=0){
parent[node] = p;
depth[node] = d;
for(int i:graph[node]){
if(i != p) dfs(i, node, d+1);
}
}
void mark_path(int idx, int u, int v){
if(depth[u] < depth[v]) swap(u, v);
for(;depth[u] > depth[v];u = parent[u]){
path[idx] |= (1LL<<u);
}
for(;u != v;u=parent[u],v=parent[v]){
path[idx] |= (1LL<<v);
path[idx] |= (1LL<<u);
}
}
int uf[MAXM];
long long union_mask[MAXM];
int fnd(int a){
return uf[a]=(uf[a]==a?a:fnd(uf[a]));
}
void un(int a, int b){
a=fnd(a);
b=fnd(b);
uf[a]=b;
union_mask[b] |= union_mask[a];
}
void reset_uf(){
for(int i=0;i<m;i++) uf[i] = i;
for(int i=0;i<m;i++) union_mask[i] = path[i];
}
int compute(int mask){
reset_uf();
for(int i=0;i<m;i++){
if(!(mask & (1<<i))) continue;
for(int j=i+1;j<m;j++){
if(!(mask & (1<<j))) continue;
if(path[i] & path[j]){
un(i, j);
}
}
}
int cnt = 0;
int not_on_paths=n-1;
for(int i=0;i<m;i++){
if(!(mask & (1<<i))) continue;
if(i != uf[i]) continue;
cnt++;
not_on_paths -= popcount(union_mask[i]);
}
//printf("%d %d %d\n", mask, cnt, not_on_paths);
return EXP(k, cnt+not_on_paths);
}
int main(){
scanf("%d%d%d", &n, &m, &k);
for(int i=0;i<n-1;i++){
int a,b;
scanf("%d%d", &a, &b);
// a--;b--;
graph[a].push_back(b);
graph[b].push_back(a);
}
dfs(1);
for(int i=0;i<m;i++){
int c,d;
scanf("%d%d", &c, &d);
// c--;d--;
mark_path(i, c, d);
}
int res=0;
for(int mask=0;mask<(1<<m);mask++){
int popcount = __builtin_popcount(mask);
if(popcount % 2 == 0){
res=ADD(res, compute(mask));
//printf("%d +%d\n", mask, compute(mask));
}else{
res=SUB(res, compute(mask));
//printf("%d -%d\n", mask, compute(mask));
}
}
printf("%d\n", res);
}
Compilation message
Main.cpp: In function 'int main()':
Main.cpp:99:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
99 | scanf("%d%d%d", &n, &m, &k);
| ~~~~~^~~~~~~~~~~~~~~~~~~~~~
Main.cpp:102:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
102 | scanf("%d%d", &a, &b);
| ~~~~~^~~~~~~~~~~~~~~~
Main.cpp:110:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
110 | scanf("%d%d", &c, &d);
| ~~~~~^~~~~~~~~~~~~~~~
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
208 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 |
1 ms |
256 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
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 |
256 KB |
Output is correct |
5 |
Correct |
1 ms |
204 KB |
Output is correct |
6 |
Correct |
0 ms |
204 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
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 |
0 ms |
204 KB |
Output is correct |
5 |
Correct |
2 ms |
204 KB |
Output is correct |
6 |
Correct |
0 ms |
204 KB |
Output is correct |
7 |
Correct |
0 ms |
204 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
0 ms |
204 KB |
Output is correct |
2 |
Correct |
1 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 |
5 ms |
204 KB |
Output is correct |
6 |
Correct |
4 ms |
216 KB |
Output is correct |
7 |
Correct |
1 ms |
216 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
208 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 |
1 ms |
256 KB |
Output is correct |
7 |
Correct |
1 ms |
204 KB |
Output is correct |
8 |
Correct |
1 ms |
204 KB |
Output is correct |
9 |
Correct |
1 ms |
204 KB |
Output is correct |
10 |
Correct |
1 ms |
256 KB |
Output is correct |
11 |
Correct |
1 ms |
204 KB |
Output is correct |
12 |
Correct |
0 ms |
204 KB |
Output is correct |
13 |
Correct |
0 ms |
204 KB |
Output is correct |
14 |
Correct |
0 ms |
204 KB |
Output is correct |
15 |
Correct |
0 ms |
204 KB |
Output is correct |
16 |
Correct |
0 ms |
204 KB |
Output is correct |
17 |
Correct |
2 ms |
204 KB |
Output is correct |
18 |
Correct |
0 ms |
204 KB |
Output is correct |
19 |
Correct |
0 ms |
204 KB |
Output is correct |
20 |
Correct |
0 ms |
204 KB |
Output is correct |
21 |
Correct |
1 ms |
204 KB |
Output is correct |
22 |
Correct |
0 ms |
204 KB |
Output is correct |
23 |
Correct |
1 ms |
204 KB |
Output is correct |
24 |
Correct |
5 ms |
204 KB |
Output is correct |
25 |
Correct |
4 ms |
216 KB |
Output is correct |
26 |
Correct |
1 ms |
216 KB |
Output is correct |
27 |
Correct |
7 ms |
216 KB |
Output is correct |
28 |
Correct |
1 ms |
216 KB |
Output is correct |
29 |
Correct |
0 ms |
216 KB |
Output is correct |
30 |
Correct |
8 ms |
212 KB |
Output is correct |
31 |
Correct |
2 ms |
212 KB |
Output is correct |
32 |
Correct |
2 ms |
280 KB |
Output is correct |
33 |
Correct |
1 ms |
204 KB |
Output is correct |
34 |
Correct |
1 ms |
204 KB |
Output is correct |
35 |
Correct |
4 ms |
280 KB |
Output is correct |
36 |
Correct |
15 ms |
280 KB |
Output is correct |
37 |
Correct |
7 ms |
276 KB |
Output is correct |