#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
#define F first
#define S second
#define pb push_back
#define endl "\n"
#define all(x) x.begin(), x.end()
const int M = 500007;
const ll inf = 1e18;
const ll mod = 1e9+7;
const double pi = acos(-1);
const int dx[] = {0, -1, 0, 1}, dy[] = {1, 0, -1, 0};
const int block = 320;
int n, cnt[M];
vector <int> v;
int main(){
cin >> n;
for(int i = 1; i < n; ++i){
int a, b;
cin >> a >> b;
++cnt[a];
++cnt[b];
}
for(int i = 1; i <= n; ++i) if(cnt[i] == 1) v.pb(i);
cout << ((int)v.size() + 1) / 2 << endl;
for(int i = 0; i < (int)v.size() - 1; i += 2) cout << v[i] << " " << v[i + 1] << endl;
if((int)v.size() % 2) cout << v.back() << " " << (v.back() == 1 ? 2 : 1) << endl;
return 0;
}
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
1 ms |
204 KB |
Output is correct |
| 2 |
Correct |
1 ms |
204 KB |
Output is correct |
| 3 |
Correct |
1 ms |
204 KB |
Output is correct |
| 4 |
Correct |
0 ms |
204 KB |
Output is correct |
| 5 |
Correct |
1 ms |
304 KB |
Output is correct |
| 6 |
Correct |
1 ms |
204 KB |
Output is correct |
| 7 |
Correct |
1 ms |
296 KB |
Output is correct |
| 8 |
Correct |
1 ms |
204 KB |
Output is correct |
| 9 |
Correct |
0 ms |
204 KB |
Output is correct |
| 10 |
Incorrect |
1 ms |
204 KB |
Breaking single line is causing network to disconnect. |
| 11 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
1 ms |
204 KB |
Output is correct |
| 2 |
Correct |
1 ms |
204 KB |
Output is correct |
| 3 |
Correct |
1 ms |
204 KB |
Output is correct |
| 4 |
Correct |
0 ms |
204 KB |
Output is correct |
| 5 |
Correct |
1 ms |
304 KB |
Output is correct |
| 6 |
Correct |
1 ms |
204 KB |
Output is correct |
| 7 |
Correct |
1 ms |
296 KB |
Output is correct |
| 8 |
Correct |
1 ms |
204 KB |
Output is correct |
| 9 |
Correct |
0 ms |
204 KB |
Output is correct |
| 10 |
Incorrect |
1 ms |
204 KB |
Breaking single line is causing network to disconnect. |
| 11 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
1 ms |
204 KB |
Output is correct |
| 2 |
Correct |
1 ms |
204 KB |
Output is correct |
| 3 |
Correct |
1 ms |
204 KB |
Output is correct |
| 4 |
Correct |
0 ms |
204 KB |
Output is correct |
| 5 |
Correct |
1 ms |
304 KB |
Output is correct |
| 6 |
Correct |
1 ms |
204 KB |
Output is correct |
| 7 |
Correct |
1 ms |
296 KB |
Output is correct |
| 8 |
Correct |
1 ms |
204 KB |
Output is correct |
| 9 |
Correct |
0 ms |
204 KB |
Output is correct |
| 10 |
Incorrect |
1 ms |
204 KB |
Breaking single line is causing network to disconnect. |
| 11 |
Halted |
0 ms |
0 KB |
- |
