Envío 5178

Código

/// Write by Daniel Perez .PERAPRO
#include<bits/stdc++.h>

using namespace std;
#define fast_io ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define pb push_back
#define ff first
#define ss second
#define all(s) s.begin(), s.end()
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
using vi=vector<int>;
using vl=vector<ll>;
using pii=pair<int,int>;
char el = '\n';
char esp = ' ';

template<class T> bool ckmin(T& a, const T& b) { return b < a ? a = b, 1 : 0; }
template<class T> bool ckmax(T& a, const T& b) { return a < b ? a = b, 1 : 0; }

ostream& operator<<(ostream& os, const vector<int> &v){
    for(auto const &i: v){
        os<<i<<" ";
    }
    os<<'\n';
    return os;
}
string yes="YES";
string no="NO";

int main(){
	fast_io;
	/*
 	freopen("input.txt","r",stdin);
    freopen("output.txt","w",stdout);
    */
    int n,a,b;
    cin>>n;
    
    vector<vi> g(n);
    for(int i=1;i<n;i++){
        cin>>a>>b;
        g[a].pb(b), g[b].pb(a);
    }
    
    int timer = 0;
    
    vi in(n), out(n);
    
    function<void(int, int)> dfs = [&] (int u, int p){
        in[u] = timer++;
        for(int v:g[u]){
            if(v == p) continue;
            dfs(v, u);
        }
        out[u] = timer;
    };
    
    dfs(0, -1);
    
    int q;
    cin>>q;
    
    //cout<<in<<out;
    
    while(q--){
        cin>>a>>b;
        //a es ancestro de b, b hace parte del subarbol de a?
        cout<<(in[b] >= in[a] && out[b] <= out[a] ? "Yes" : "No")<<el;
    }
}

/*

*/