| # |
Submission time |
Handle |
Problem |
Language |
Result |
Execution time |
Memory |
| 895965 |
2023-12-31T08:47:51 Z |
thunopro |
Network (BOI15_net) |
C++14 |
|
2 ms |
12892 KB |
#include<bits/stdc++.h>
using namespace std ;
#define ll long long
#define maxn 500009
#define fi first
#define se second
#define pb push_back
#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 ;
const int LOG = 18 ;
typedef vector<int> vi ;
typedef pair<int,int> pii ;
typedef vector<ll> vl ;
typedef vector<pii> vii ;
void add ( int &a , int b )
{
a += b ;
if ( a < 0 ) a += mod ;
if ( a >= mod ) a -= mod ;
}
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 rf ()
{
freopen ("bai1.inp","r",stdin) ;
// freopen ("bai1.out","w",stdout) ;
}
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 n ;
int deg [maxn] ;
vi adjList [maxn] ;
vi leaves ;
void dfs ( int u , int par = 0 )
{
if ( deg [u] == 1 ) leaves.pb (u) ;
for ( auto v : adjList [u] )
{
if ( v == par ) continue ;
dfs (v,u) ;
}
}
int main ()
{
ios_base::sync_with_stdio(0);
cin.tie(0);cout.tie(0) ;
// rf () ;
cin >> n ;
for ( int i = 1 ; i < n ; i ++ )
{
int u , v ; cin >> u >> v ;
deg [u] ++ , deg [v] ++ ;
adjList [u] . pb (v) ;
adjList [v] . pb (u) ;
}
int root = 0 ;
for ( int i = 1 ; i <= n ; i ++ ) if ( deg [i] > 1 ) root = i ;
dfs (root) ;
cout << (leaves.size()+1)/2 << "\n" ;
for ( int i = 0 ; i < leaves.size () ; i ++ )
{
if ( i == leaves.size () - 1 )
{
cout << leaves.back () << " " << leaves [0] << "\n" ;
}
else cout << leaves.back() << " " << leaves [i] << "\n" ;
leaves.pop_back () ;
}
}
// range , error , check special , ...
// find key , find key
//'-std=c++11' stay hard
// there is no tomorrow
Compilation message
net.cpp: In function 'int main()':
net.cpp:76:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
76 | for ( int i = 0 ; i < leaves.size () ; i ++ )
| ~~^~~~~~~~~~~~~~~~
net.cpp:78:10: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
78 | if ( i == leaves.size () - 1 )
| ~~^~~~~~~~~~~~~~~~~~~~~
net.cpp: In function 'void rf()':
net.cpp:34:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
34 | freopen ("bai1.inp","r",stdin) ;
| ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
2 ms |
12892 KB |
Output is correct |
| 2 |
Incorrect |
2 ms |
12892 KB |
Breaking single line is causing network to disconnect. |
| 3 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
2 ms |
12892 KB |
Output is correct |
| 2 |
Incorrect |
2 ms |
12892 KB |
Breaking single line is causing network to disconnect. |
| 3 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
2 ms |
12892 KB |
Output is correct |
| 2 |
Incorrect |
2 ms |
12892 KB |
Breaking single line is causing network to disconnect. |
| 3 |
Halted |
0 ms |
0 KB |
- |
