Submission #2965791

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Source Code Expand

#include<iostream>
#include<string>
#include<algorithm>
#include<vector>
#include<iomanip>
#include<math.h>
#include<complex>
#include<queue>
#include<deque>
#include<map>
#include<set>
#include<bitset>
using namespace std;
#define REP(i,m,n) for(int i=(int)m ; i < (int) n ; i++ )
#define rep(i,n) REP(i,0,n)
typedef long long ll;
typedef pair<int,int> pint;
typedef pair<ll,int> pli;
const int inf=1e9+7;
const ll longinf=1LL<<60 ;
const ll mod=1e9+7 ;
const ll mod2=1e9+9 ;
int dx[4]={1,0,-1,0} , dy[4]={0,1,0,-1} ;

int n,h=20;
vector<vector<int>> v,par;
vector<int> depth;

void dfs(int x,int p,int d){
    par[0][x]=p;
    depth[x]=d;
    for(auto to:v[x])if(to!=p)dfs(to,x,d+1);
}

void build(){
    depth.resize(n);
    par.assign(h,vector<int>(n,-1));
    dfs(0,-1,0);
    rep(i,h-1){
        rep(j,n){
            if(par[i][j]<0)par[i+1][j]=-1;
            else par[i+1][j]=par[i][par[i][j]];
        }
    }
}

int lca(int u,int v){
    if(depth[u]>depth[v])swap(u,v);
    rep(i,h)if((depth[v]-depth[u])>>i &1)v=par[i][v];
    if(u==v)return u;
    for(int i=h-1;i>=0;i--){
        if(par[i][u]!=par[i][v]){
            u=par[i][u];
            v=par[i][v];
        }
    }
    return par[0][u];
}

int dist(int u,int v){
    return depth[u]+depth[v]-2*depth[lca(u,v)];
}

int ord[101010];
void dfs2(int x,int p,int& i){
  for(auto to:v[x]){
    if(to==p)continue;
    dfs2(to,x,i);
    }
  ord[x]=i;
  i++;
  }

bool cmp(int x,int y){
  return ord[x]>ord[y];
  }
 

int main(){
    cin>>n;
    v.resize(n);
    rep(i,n-1){
        int x,y;
        cin>>x>>y;
        x--;y--;
        v[x].push_back(y);
        v[y].push_back(x);
    }
    build();
    int i=0;
    dfs2(0,-1,i);
    int q;
    cin>>q;
    rep(aaa,q){
      int m,k;cin>>m>>k;
      vector<int> w;
      rep(i,m){
        int r;cin>>r;
        w.push_back(r-1);
        }
      sort(w.begin(),w.end(),cmp);
      int ans=-1;
      rep(i,m-k+1){
        int ret=lca(w[i],w[i+k-1]);
        ans=max(ans,depth[ret]);
        }
      cout<<ans<<endl;
      }
  
    return 0;
}

Submission Info

Judge Result