#include <bits/stdc++.h>
using namespace std;
int n;
bool Free[500005];
vector<int> V,g[500005];
inline void DFS(int u)
{
Free[u]=true;
if(g[u].size()==1)
{
V.push_back(u);
return;
}
for(int i=0;i<g[u].size();i++)
if(Free[g[u][i]]==false)
DFS(g[u][i]);
}
int main()
{
ios_base::sync_with_stdio(false);
//freopen("NET.INP","r",stdin);
cin>>n;
int u,v;
for(int i=1;i<n;i++)
{
cin>>u>>v;
g[u].push_back(v);
g[v].push_back(u);
}
for(int i=1;i<=n;i++)
if(g[i].size()>=2)
{
DFS(i);
break;
}
int tmp=V.size();
cout<<(tmp+1)/2<<"\n";
for(int i=0;i<=(tmp-1)/2;i++)
cout<<V[i]<<' '<<V[i+tmp/2]<<"\n";
}
Compilation message
net.cpp: In function 'void DFS(int)':
net.cpp:16:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for(int i=0;i<g[u].size();i++)
^
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
0 ms |
14380 KB |
Output is correct |
2 |
Correct |
0 ms |
14380 KB |
Output is correct |
3 |
Correct |
3 ms |
14380 KB |
Output is correct |
4 |
Correct |
3 ms |
14380 KB |
Output is correct |
5 |
Correct |
3 ms |
14380 KB |
Output is correct |
6 |
Correct |
3 ms |
14380 KB |
Output is correct |
7 |
Correct |
6 ms |
14380 KB |
Output is correct |
8 |
Correct |
3 ms |
14380 KB |
Output is correct |
9 |
Correct |
3 ms |
14380 KB |
Output is correct |
10 |
Correct |
0 ms |
14380 KB |
Output is correct |
11 |
Correct |
0 ms |
14380 KB |
Output is correct |
12 |
Correct |
0 ms |
14380 KB |
Output is correct |
13 |
Correct |
0 ms |
14380 KB |
Output is correct |
14 |
Correct |
0 ms |
14380 KB |
Output is correct |
15 |
Correct |
3 ms |
14380 KB |
Output is correct |
16 |
Correct |
3 ms |
14380 KB |
Output is correct |
17 |
Correct |
3 ms |
14380 KB |
Output is correct |
18 |
Correct |
9 ms |
14380 KB |
Output is correct |
19 |
Correct |
3 ms |
14380 KB |
Output is correct |
20 |
Correct |
6 ms |
14380 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
0 ms |
14380 KB |
Output is correct |
2 |
Correct |
0 ms |
14380 KB |
Output is correct |
3 |
Correct |
3 ms |
14380 KB |
Output is correct |
4 |
Correct |
3 ms |
14380 KB |
Output is correct |
5 |
Correct |
3 ms |
14380 KB |
Output is correct |
6 |
Correct |
3 ms |
14380 KB |
Output is correct |
7 |
Correct |
6 ms |
14380 KB |
Output is correct |
8 |
Correct |
3 ms |
14380 KB |
Output is correct |
9 |
Correct |
3 ms |
14380 KB |
Output is correct |
10 |
Correct |
0 ms |
14380 KB |
Output is correct |
11 |
Correct |
0 ms |
14380 KB |
Output is correct |
12 |
Correct |
0 ms |
14380 KB |
Output is correct |
13 |
Correct |
0 ms |
14380 KB |
Output is correct |
14 |
Correct |
0 ms |
14380 KB |
Output is correct |
15 |
Correct |
3 ms |
14380 KB |
Output is correct |
16 |
Correct |
3 ms |
14380 KB |
Output is correct |
17 |
Correct |
3 ms |
14380 KB |
Output is correct |
18 |
Correct |
9 ms |
14380 KB |
Output is correct |
19 |
Correct |
3 ms |
14380 KB |
Output is correct |
20 |
Correct |
6 ms |
14380 KB |
Output is correct |
21 |
Correct |
3 ms |
14380 KB |
Output is correct |
22 |
Runtime error |
3 ms |
14380 KB |
Execution killed because of forbidden syscall writev (20) |
23 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
0 ms |
14380 KB |
Output is correct |
2 |
Correct |
0 ms |
14380 KB |
Output is correct |
3 |
Correct |
3 ms |
14380 KB |
Output is correct |
4 |
Correct |
3 ms |
14380 KB |
Output is correct |
5 |
Correct |
3 ms |
14380 KB |
Output is correct |
6 |
Correct |
3 ms |
14380 KB |
Output is correct |
7 |
Correct |
6 ms |
14380 KB |
Output is correct |
8 |
Correct |
3 ms |
14380 KB |
Output is correct |
9 |
Correct |
3 ms |
14380 KB |
Output is correct |
10 |
Correct |
0 ms |
14380 KB |
Output is correct |
11 |
Correct |
0 ms |
14380 KB |
Output is correct |
12 |
Correct |
0 ms |
14380 KB |
Output is correct |
13 |
Correct |
0 ms |
14380 KB |
Output is correct |
14 |
Correct |
0 ms |
14380 KB |
Output is correct |
15 |
Correct |
3 ms |
14380 KB |
Output is correct |
16 |
Correct |
3 ms |
14380 KB |
Output is correct |
17 |
Correct |
3 ms |
14380 KB |
Output is correct |
18 |
Correct |
9 ms |
14380 KB |
Output is correct |
19 |
Correct |
3 ms |
14380 KB |
Output is correct |
20 |
Correct |
6 ms |
14380 KB |
Output is correct |
21 |
Correct |
3 ms |
14380 KB |
Output is correct |
22 |
Runtime error |
3 ms |
14380 KB |
Execution killed because of forbidden syscall writev (20) |
23 |
Halted |
0 ms |
0 KB |
- |