#include <bits/stdc++.h>
using namespace std;
#define endl '\n'
#define ll long long
const ll MOD = 1e9 + 7, MAX = 5e5 + 5, INF = 1e18;
vector <int> dx = { 1, 0, 0, -1, 1, 1, -1, -1 };
vector <int> dy = { 0, 1, -1, 0, -1, 1, 1, -1 };
ll gcd(ll a, ll b) { return b ? gcd(b, a % b) : a; }
ll lcm(ll a, ll b) { return (a / gcd(a, b)) * b; }
vector <ll> adj[MAX];
int main()
{
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
//freopen("", "r", stdin);
//freopen("", "w", stdout);
vector <ll> frq(MAX);
ll n;
cin >> n;
for (ll i = 0; i < n - 1; i++)
{
ll u, v;
cin >> u >> v;
u--, v--;
adj[u].push_back(v);
adj[v].push_back(u);
frq[u]++, frq[v]++;
}
ll sum = 0, prv;
for (ll i = 0; i < n; i++)
{
if (frq[i] < 2)
{
sum++;
}
}
cout << ceil(sum * 1.0 / 2.0) << endl;
sum = 0;
for (ll i = 0; i < n; i++)
{
if (frq[i] < 2)
{
sum++;
if (sum % 2 == 0)
{
cout << prv + 1 << " " << i + 1 << endl;
adj[prv].push_back(i);
adj[i].push_back(prv);
}
prv = i;
}
}
if (sum % 2 != 0)
{
for (ll i = n - 1; i >= 0; i--)
{
if (frq[i] < 2)
{
for (ll j = 0; j < n; j++)
{
bool flag = 0;
for (auto child : adj[i])
{
if (child == j)
{
flag = 1;
break;
}
}
if (!flag)
{
cout << i + 1 << " " << j + 1 << endl;
return 0;
}
}
}
}
}
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
8 ms |
15956 KB |
Output is correct |
2 |
Correct |
8 ms |
15956 KB |
Output is correct |
3 |
Correct |
8 ms |
15956 KB |
Output is correct |
4 |
Correct |
8 ms |
15956 KB |
Output is correct |
5 |
Correct |
7 ms |
15956 KB |
Output is correct |
6 |
Correct |
8 ms |
15956 KB |
Output is correct |
7 |
Correct |
8 ms |
15932 KB |
Output is correct |
8 |
Correct |
8 ms |
15956 KB |
Output is correct |
9 |
Correct |
8 ms |
15920 KB |
Output is correct |
10 |
Incorrect |
7 ms |
15956 KB |
Breaking single line is causing network to disconnect. |
11 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
8 ms |
15956 KB |
Output is correct |
2 |
Correct |
8 ms |
15956 KB |
Output is correct |
3 |
Correct |
8 ms |
15956 KB |
Output is correct |
4 |
Correct |
8 ms |
15956 KB |
Output is correct |
5 |
Correct |
7 ms |
15956 KB |
Output is correct |
6 |
Correct |
8 ms |
15956 KB |
Output is correct |
7 |
Correct |
8 ms |
15932 KB |
Output is correct |
8 |
Correct |
8 ms |
15956 KB |
Output is correct |
9 |
Correct |
8 ms |
15920 KB |
Output is correct |
10 |
Incorrect |
7 ms |
15956 KB |
Breaking single line is causing network to disconnect. |
11 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
8 ms |
15956 KB |
Output is correct |
2 |
Correct |
8 ms |
15956 KB |
Output is correct |
3 |
Correct |
8 ms |
15956 KB |
Output is correct |
4 |
Correct |
8 ms |
15956 KB |
Output is correct |
5 |
Correct |
7 ms |
15956 KB |
Output is correct |
6 |
Correct |
8 ms |
15956 KB |
Output is correct |
7 |
Correct |
8 ms |
15932 KB |
Output is correct |
8 |
Correct |
8 ms |
15956 KB |
Output is correct |
9 |
Correct |
8 ms |
15920 KB |
Output is correct |
10 |
Incorrect |
7 ms |
15956 KB |
Breaking single line is causing network to disconnect. |
11 |
Halted |
0 ms |
0 KB |
- |