이 제출은 이전 버전의 oj.uz에서 채점하였습니다. 현재는 제출 당시와는 다른 서버에서 채점을 하기 때문에, 다시 제출하면 결과가 달라질 수도 있습니다.
#include <bits/stdc++.h>
using namespace std;
const int mxn =2e5+10;
int pre[mxn];
vector<int> tree[mxn];
vector<int> dir[mxn];
bitset<255> used;
int m;
int n;
void dfs(int now,int par){
pre[now] = par;
for(auto nxt:tree[now]){
if(nxt == par)continue;
dfs(nxt,now);
}
return;
}
bool f(int arr[]){
bitset<255> tmp;
for(int i = 1;i<=n;i++)tmp[i] = used[i];
bool flag = true;
// for(int i = 0;i<m;i++)cout<<arr[i]<<',';cout<<endl;
for(int i = 0;i<m;i++){
int now = arr[i];
for(auto &j:dir[now])if(j != dir[now].back()&&tmp[j])flag = false;
tmp[dir[now].back()] = false;
tmp[dir[now][0]] = true;
// for(int j = 1;j<=n;j++)cout<<tmp[j];cout<<endl;
}
if(flag)return true;
else return false;
}
void solve1(){
pair<int,int> arr[m];
for(auto &i:arr)cin>>i.first>>i.second;
sort(arr,arr+m);
int maxR = 0,minL = 0;
bool flag = true;
for(auto &i:arr){
if(i.first>i.second){
if(minL>i.second)flag = false;
if(maxR>i.second)flag = false;
minL = max(minL,i.second);
}
else{
if(maxR>i.second)flag = false;
maxR = max(maxR,i.second);
}
}
if(flag)cout<<"Yes\n";
else cout<<"No\n";
return;
}
void solve(){
cin>>n;
for(int i = 0;i<n-1;i++){
int a,b;
cin>>a>>b;
tree[a].push_back(b);
tree[b].push_back(a);
}
cin>>m;
if(m>6||n>250){
solve1();
return;
}
for(int i = 0;i<m;i++){
int s,e;
cin>>s>>e;
used[s] = true;
dfs(s,s);
int tmp = e;
dir[i].push_back(e);
while(tmp != s){
dir[i].push_back(tmp=pre[tmp]);
}
// for(int j = 1;j<=n;j++)cout<<pre[j]<<',';cout<<endl;
// for(auto &j:dir[i])cout<<j<<',';cout<<endl;
}
int choice[m];
for(int i = 0;i<m;i++)choice[i] = i;
bool flag = false;
if(f(choice))flag = true;
while(next_permutation(choice,choice+m))if(f(choice))flag = true;
if(flag)cout<<"Yes\n";
else cout<<"No\n";
for(int i = 0;i<=n;i++){
tree[i].clear();
}
for(int i =0;i<m;i++)dir[i].clear();
used.reset();
return;
}
int main(){
ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
int t;
cin>>t;
while(t--)solve();
}
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