#include<bits/stdc++.h>
using namespace std ;
#define maxn 200009
#define ll long long
#define pb push_back
#define fi first
#define se second
#define left id<<1
#define right id<<1|1
#define re exit(0);
#define _lower(x) lower_bound(v.begin(),v.end(),x)-v.begin()+1
const int mod = 1e9+7 ;
const int INF = 1e9 ;
typedef vector<int> vi ;
typedef pair<int,int> pii ;
typedef vector<pii> vii ;
template < typename T > void chkmin ( T &a , T b ) { if ( a > b ) a = b ; }
template < typename T > void chkmax ( T &a , T b ) { if ( a < b ) a = b ; }
void add ( int &a , int b )
{
a += b ;
if ( a >= mod ) a -= mod ;
if ( a < 0 ) a += mod ;
}
void rf ()
{
freopen ("bai1.inp","r",stdin) ;
}
int _pow ( int a , int n )
{
if ( n == 0 ) return 1 ;
int res = _pow (a,n/2) ;
if ( n % 2 ) return 1ll*res*res%mod*a%mod ;
else return 1ll*res*res%mod ;
}
//int query ( vi v ) ;
//int solve ( vi v ) ;
//int findEgg ( int N , vii bridges ) ;
//int main ()
//{
// ios_base::sync_with_stdio(0);
// cin.tie(0);cout.tie(0);
//// rf () ;
// int n ;
// vii bridges ;
// cin >> n ;
// for ( int i = 1 ; i < n ; i ++ )
// {
// int u , v ; cin >> u >> v ;
// bridges . pb ({u,v}) ;
// }
// cout << findEgg (n,bridges) ;
//}
//
//int query ( vi v )
//{
// for ( auto x : v ) cerr << x << "\n" ;
// int z ; cin >> z ;
// return z ;
//}
int n ; vi adjList [maxn] ;
int tin [maxn] , tout [maxn] , timeDfs , sz [maxn] ;
int dfs ( int u , int par = -1 )
{
sz [u] = 1 , tin [u] = ++ timeDfs ;
for ( auto v : adjList [u] )
{
if ( v == par ) continue ;
sz [u] += dfs (v,u) ;
}
tout [u] = timeDfs ;
return sz [u] ;
}
int solve ( vi vertex )
{
if ( vertex.size() == 1 ) return vertex.back() ;
for ( auto x : vertex ) sz [x] = 0 ;
int n = dfs (vertex[0]) ;
timeDfs = 0 ;
int Min = INF , ver = -1 ;
for ( auto x : vertex )
{
if ( abs(2*sz[x]-n) < Min )
{
Min = abs(2*sz[x]-n) ;
ver = x ;
}
}
vi island1 , island2 ;
for ( auto x : vertex )
{
if ( tin [ver] <= tin [x] && tin [x] <= tout [ver] ) island1 . pb (x) ;
else island2 . pb (x) ;
}
if ( query(island1) == true ) return solve(island1) ;
else return solve(island2) ;
}
int findEgg ( int N , vii bridges )
{
n = N ;
for ( auto x : bridges ) adjList[x.fi] . pb (x.se) , adjList[x.se] . pb (x.fi) ;
vi vertex ;
for ( int i = 1 ; i <= n ; i ++ ) vertex . pb (i) ;
return solve(vertex) ;
}
Compilation message
eastereggs.cpp: In function 'int solve(vi)':
eastereggs.cpp:103:7: error: 'query' was not declared in this scope
103 | if ( query(island1) == true ) return solve(island1) ;
| ^~~~~
eastereggs.cpp: In function 'void rf()':
eastereggs.cpp:31:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
31 | freopen ("bai1.inp","r",stdin) ;
| ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
eastereggs.cpp: In function 'int solve(vi)':
eastereggs.cpp:97:5: warning: control reaches end of non-void function [-Wreturn-type]
97 | vi island1 , island2 ;
| ^~~~~~~
