#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0;i<n;i++)
#define per(i,n) for(int i=n-1;i>=0;i--)
#define rng(i,c,n) for(int i=c;i<n;i++)
#define fi first
#define se second
#define pb push_back
#define sz(a) (int)a.size()
#define vec(...) vector<__VA_ARGS__>
#define _3xaMC2q ios::sync_with_stdio(0),cin.tie(0)
typedef long long ll;
using pii=pair<int,int>;
using vi=vector<int>;
void print(){cout<<'\n';}
template<class h,class...t>
void print(const h&v,const t&...u){cout<<v<<' ',print(u...);}
//e
#define vp vec(pii)
const int _n=300011,lon=19;
int n,m;
vi adj[_n];
map<pii,int> es;
int spr[lon][_n],prs[lon][_n];
int par[_n],dpth[_n],tin[_n];
int _tm;
vi tour;
void dfs(int v){
tin[v]=_tm++;
tour.pb(v);
for(auto u:adj[v]){
if(u==par[v]) continue;
dpth[u]=dpth[v]+1;
par[u]=v;
dfs(u);
tour.pb(v);
_tm++;
}
}
int chmin(int v,int u){
return dpth[v]<dpth[u]?v:u;
}
void _gap_lca(){
dfs(0);
rep(i,n){
prs[0][i]=par[i];
}
rng(j,1,lon){
rep(i,n){
int up=prs[j-1][i];
prs[j][i]=up==-1?up:prs[j-1][up];
}
}
const int si_to=sz(tour);
rep(i,si_to){
spr[0][i]=tour[i];
if(i+1<si_to){
spr[0][i]=chmin(spr[0][i],tour[i+1]);
}
}
rng(j,1,lon){
rep(i,si_to){
int up=spr[j-1][i];
if(i+(1<<(j-1))<si_to){
up=chmin(up,spr[j-1][i+(1<<(j-1))]);
}
spr[j][i]=up;
}
}
}
int get_ancestor(int u,int v){
int i=tin[u],j=tin[v];
if(i==j) return v;
if(i>j)swap(i,j),swap(u,v);
int k=31-__builtin_clz(j-i);
u=spr[k][i];
v=spr[k][j-(1<<k)];
return chmin(u,v);
}
int get_dist(int u,int v){
int up=get_ancestor(u,v);
return dpth[v]+dpth[u]-2*dpth[up];
}
int push_up(int s,int d){
per(i,lon){
if(d>>i&1){
s=prs[i][s];
}
}
return s;
}
signed main(){
_3xaMC2q;
cin>>n>>m;
rep(i,n-1){
int u,v;
cin>>u>>v;
u-=1,v-=1;
es[minmax(u,v)]=i;
adj[u].pb(v);
adj[v].pb(u);
}
_gap_lca();
// vi rbe(n,-1);
// //denotes edge from (i,pari)
// vec(vp) g(n-1);
// //denotes graph of edges in inital graph
// rep(i,m){
// int s,t;
// cin>>s>>t;
// s-=1,t-=1;
// if(dpth[s]>dpth[t])swap(s,t);
// if(s!=t){
// int up=get_ancestor(s,t);
// if(up!=s){
// int ds=get_dist(s,up);
// int ns=push_up(s,ds-1);
// int id=s;
// rbe[id]=rbe[id]==-1?ns:chmin(rbe[id],ns);
// int dt=get_dist(t,up);
// int nt=push_up(t,dt-1);
// id=t;
// rbe[id]=rbe[id]==-1?nt:chmin(rbe[id],nt);
// int u=es[minmax(ns,up)],v=es[minmax(nt,up)];
// g[u].pb(pii(1,v));
// g[v].pb(pii(1,u));
// }else{
// int dt=get_dist(t,up);
// int nt=push_up(t,dt-1);
// int id=t;
// rbe[id]=rbe[id]==-1?nt:chmin(rbe[id],nt);
// }
// }
// }
// //add additional edges from rbe
// vi rbts;
// rep(i,n)rbts.pb(i);
// sort(rbts.begin(),rbts.end(),[&](int l,int r){return dpth[l]>dpth[r];});
// for(auto s:rbts){
// if(rbe[s]!=-1){
// if(dpth[rbe[s]]<dpth[s]){
// int up=rbe[s];
// rbe[par[s]]=rbe[par[s]]==-1?up:chmin(rbe[par[s]],up);
// int u=es[minmax(s,par[s])],v=es[minmax(par[s],par[par[s]])];
// g[u].pb(pii(0,v));
// g[v].pb(pii(0,u));
// }
// }
// }
// bool valid=1;
// vi usd(n-1,-1);
// auto rfs=[&](auto self,int v)->void{
// for(auto e:g[v]){
// int u=e.se;
// int w=e.fi;
// if(usd[u]==-1){
// usd[u]=usd[v]^w;
// self(self,u);
// }else if(usd[u]!=(usd[v]^w)){
// valid=0;
// }
// }
// };
// ll ans=1;
// const ll mod=1000000007;
// rep(i,n-1){
// if(usd[i]==-1){
// usd[i]=0;
// ans=ans*2%mod;
// ans%=mod;
// rfs(rfs,i);
// }
// }
// if(!valid){
// print(0);
// }else{
// print(ans);
// }
}
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
69 ms |
47552 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
173 ms |
104888 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
6 ms |
7892 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
4 ms |
7892 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
8 ms |
9340 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
7 ms |
9300 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
325 ms |
86616 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
387 ms |
86560 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
320 ms |
86876 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
392 ms |
87020 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
