Hackerearth_Bishu_and_his_Girlfriend.cpp

#include <bits/stdc++.h>
using namespace std;
#define F first
#define S second
#define PB push_back
#define PF push_front
#define P push
#define INC(i,a,b) for (ll i = a; i <= b; i++)
#define DEC(i,b,a) for (ll i = b; i >= a ; i--)
#define inf LLONG_MAX
#define neginf LLONG_MIN
#define mod  1000000007
#define eps 1e-9
typedef ostringstream OS ;
typedef stringstream SS ;
typedef long long ll ;
typedef unsigned long long ull;
typedef pair < ll , ll > PLL ;
typedef pair < char,ll > PCL ;
typedef deque < double > DD ;
typedef deque < PCL > DCL ;
typedef deque < ll > DL ;
typedef deque < PLL > DLL ;
typedef deque < char > DC ;
typedef deque < string > DS ;
typedef vector < double > VD;
typedef vector < PCL > VCL ;
typedef vector < ll > VL;
typedef vector < PLL > VLL ;
typedef vector < char > VC ;
typedef vector < string > VS ;
typedef map < ll ,ll > MLL ;
typedef map < char,ll > MCL;
typedef map < ll,char > MLC;
typedef map < string,ll> MSL;
typedef priority_queue < PLL > PQLL ;
typedef priority_queue < ll > PQL ;
typedef stack < ll > SKL ;
typedef stack < PLL > SKLL ;
typedef queue < ll > QL ;
typedef queue < PLL > QLL ;
typedef set < ll > SL ;
typedef set < PLL > SLL ;
typedef set < char > SC ;
 
string numtostr(ll n) {
     OS str1 ;
     str1 << n ;
     return str1.str();
}
ll strtonum(string s) {
     ll x ;
     SS str1(s);
     str1 >> x ;
     return x ;
}
ll GCD(ll a, ll b) {
    if ( b == 0 ) return a ;
    else return GCD(b,a%b);
}
ll LCM(ll a , ll b) {
    ll gcd = GCD(a,b);
     return (a/gcd)*b ;
}
vector < VL > graph ;
VL visited ;
VL dis;
void dfs( ll x , ll len) {
    visited[x] = 1 ;
    dis[x] = len ;
    if ( graph[x].size() > 0 ) {
        INC(i,0,graph[x].size()-1) {
            if ( !visited[graph[x][i]]) dfs(graph[x][i],len+1);
        }
    }
}
 
int main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    ll n ;
	cin >> n ;
	graph.resize(n+5);
    visited.resize(n+5,0);
	dis.resize(n+5,0);
	INC(i,0,n-2) {
		ll node1,node2 ;
		cin >> node1 >> node2 ;
		graph[node1].PB(node2);
	}
    dfs(1,0);
    ll q ;
    cin >> q ;
    VL query ;
    INC(i,0,q-1) {
        ll a;
        cin >> a ;
        query.PB(a);
    }   
    sort(query.begin(),query.end());
    ll minimum = inf ;
    ll result = -1 ;
    INC(i,0,query.size()-1) {
        if ( dis[query[i]] < minimum) {
            minimum = dis[query[i]];
            result = query[i];
        }
    }
    cout << result << endl;
 
    return 0 ;
}