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| #include <bits/stdc++.h>
using namespace std;
const double eps = 1e-10;
const double pi = 3.1415926535897932384626433832795;
const double eln = 2.718281828459045235360287471352;
#define f(i, a, b) for (int i = a; i <= b; i++)
#define scan(x) scanf("%d", &x)
#define mp make_pair
#define pb push_back
#define lowbit(x) (x&(-x))
#define fi first
#define se second
#define SZ(x) int((x).size())
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define summ(a) (accumulate(all(a), 0ll))
typedef unsigned long long ull;
typedef pair<int,int> pii;
typedef vector<int> vi;
using ll=long long;
ll tt,n;
ull hsh[(int)2e5+9];
vector<int> g[(int)2e5+9];
ll h(ll x) {
return x * x * x * 1237123 + 19260817;
}
ll ff(ll x) {
ll cur = h(x & ((1ll << 31) - 1)) + h(x >> 31);
return cur;
}
void dfs(int u,int fa){
for(auto it:g[u])if(it!=fa){
dfs(it,u);
hsh[u]+=ff(hsh[it]);
}
}
bool check(int u,int fa){
map<ull,vi> wz;
ll cnt=0;
for(auto it:g[u])if(it!=fa){
wz[hsh[it]].push_back(it);
}
for(auto [aa,bb]:wz)cnt+=(((int)bb.size())&1);
if(cnt>1)return false;
if(cnt<1)return true;
for(auto [_,bb]:wz){
if(bb.size()&1){
bool ok=false;
for(auto it:bb)ok|=check(it,u);
return ok;
}
}
return false;
}
bool solve(){
cin>>n;
for(int i=1;i<=n;++i)g[i].clear(),hsh[i]=1;
for(int i=1,x,y;i<n;++i){
cin>>x>>y;
g[x].push_back(y),g[y].push_back(x);
}
dfs(1,0);
return check(1,0);
}
int main()
{
ios::sync_with_stdio(false);
cin.tie(0);
cin>>tt;
f(sb,1,tt)cout<<(solve()?"YES\n":"NO\n");
return 0;
}
|