#include<iostream>
#include<stack>
#include<map>
#include<vector>
#include<string>
#include<unordered_map>
#include <queue>
#include<cstring>
#include<float.h>
#include<limits.h>
#include <cassert>
#include<cmath>
#include<set>
#include<algorithm>
#include <iomanip>
#include<numeric> //gcd(a,b)
#include<bitset>
using namespace std;
#define ll long long
#define f first
#define endl "\n"
#define s second
#define pii pair<int,ll>
#define ppii pair<int,pii>
#define vi vector<int>
#define pb push_back
#define all(x) x.begin(),x.end()
#define rall(x) x.rbegin(),x.rend()
#define F(n) for(int i=0;i<n;i++)
#define lb lower_bound
#define ub upper_bound
using namespace std;
#define int long long
#define double long double
#define fastio ios::sync_with_stdio(false);cin.tie(NULL);
#pragma GCC optimize ("03,unroll-loops")
const int mod=1e9+7,mxn=3e5,lg=30,inf=1e18,minf=-1e9,Mxn=100000;
int n,m;
vector<int>adj[mxn+10];
int up[mxn+10][lg+5],h[mxn+10],pa[mxn+10],val[mxn+10],sz[mxn+10];
int ans=1;
int find(int u){return ((pa[u]==u)?u:pa[u]=find(pa[u]));}
void get(int cur,int p){for(auto i:adj[cur])if(i!=p)h[i]=h[cur]+1,up[i][0]=cur,get(i,cur);}
void merg(int a,int b){
a=find(a),b=find(b);
if(a==b)return;
if(h[a]>h[b])swap(a,b);
pa[b]=a;
}
int lca(int a,int b){
if(h[a]<h[b])swap(a,b);
int k=h[a]-h[b];
for(int i=0;i<=lg;i++)if(k&(1<<i))a=up[a][i];
if(a==b)return a;
for(int i=lg;i>=0;i--)if(up[a][i]!=up[b][i])a=up[a][i],b=up[b][i];
return up[a][0];
}
void goup(int cur,int node){
while(h[cur]>h[node]+1){
merg(cur,up[cur][0]);
cur=find(cur);
}
}
vector<int>bi[mxn+10];
void checkbi(int cur,int col){
if(val[cur]!=0&&val[cur]!=col)return void(ans=0);
val[cur]=col;
for(auto &i:bi[cur]){
i=find(i);
if(val[i]!=0&&val[i]!=((col==1)?-1:1))ans=0;
else if(val[i]==0)checkbi(i,((col==1)?-1:1));
}
}
int32_t main(){
fastio
cin>>n>>m;
vector<pii>check(m);
for(int i=0;i<n-1;i++){
int a,b;cin>>a>>b;
adj[a].pb(b);
adj[b].pb(a);
}
get(1,-1);
for(int i=1;i<=n;i++)pa[i]=i,sz[i]=1;
for(int i=0;i<m;i++)cin>>check[i].f>>check[i].s;
for(int j=0;j<=lg;j++)up[1][j]=1;
for(int j=1;j<=lg;j++)for(int i=2;i<=n;i++)up[i][j]=up[up[i][j-1]][j-1];
for(auto i:check){
int node=lca(i.f,i.s);
if(i.f!=node)goup(i.f,node);
if(i.s!=node)goup(i.s,node);
if(i.f==node||i.s==node)continue;
bi[i.f].pb(i.s);
bi[i.s].pb(i.f);
}
for(int i=2;i<=n;i++)if(!val[find(i)])checkbi(i,1),ans=(ans*2)%mod;
cout<<ans<<'\n';
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
88 ms |
60760 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
209 ms |
128848 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Incorrect |
6 ms |
23900 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Incorrect |
6 ms |
23900 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Incorrect |
10 ms |
24412 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Incorrect |
9 ms |
24408 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Incorrect |
279 ms |
123740 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Incorrect |
365 ms |
128084 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Incorrect |
313 ms |
128084 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Incorrect |
339 ms |
128604 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |