#include <bits/stdc++.h>
#pragma GCC optimize("O3", "unroll-loops")
#define ll long long
#define int long long
#define pb push_back
#define fi first
#define se second
#define lf (id<<1)
#define rg ((id<<1)|1)
#define md ((l+r)>>1)
#define ld long double
using namespace std;
typedef pair<int,int> pii;
typedef pair<pii, int> ipii;
const int MAXN = 3e3+10;
const int INF = 1e18+10;
const int LOG = 19;
const int MOD = 1e9+7;
const int SQRT = 450;
const vector<int> NOL = {};
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
const vector<int> dx = {1, -1, 0, 0};
const vector<int> dy = {0, 0, 1, -1};
int n;
vector <int> adj[MAXN];
signed main(){
// ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
cin >> n;
for(int i=1; i<=n-1; i++){
int x, y; cin >> x >> y;
adj[x].pb(y); adj[y].pb(x);
}
vector <int> leaf;
for(int i=1; i<=n; i++){
if(adj[i].size()==1) leaf.pb(i);
}
vector <pii> ans;
if(leaf.size()==2) ans.pb({leaf[0], leaf[1]});
else if(leaf.size()==3){
ans.pb({leaf[0], leaf[1]}); ans.pb({leaf[1], leaf[2]});
} else {
ans.pb({leaf[0], leaf[1]});
for(int i=3; i<leaf.size(); i++) ans.pb({leaf[i-1], leaf[i]});
}
cout << ans.size() << '\n';
for(auto in : ans) cout << in.fi << ' ' << in.se << '\n';
}
Compilation message
net.cpp: In function 'int main()':
net.cpp:45:17: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
45 | for(int i=3; i<leaf.size(); i++) ans.pb({leaf[i-1], leaf[i]});
| ~^~~~~~~~~~~~
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
0 ms |
344 KB |
Output is correct |
2 |
Incorrect |
0 ms |
344 KB |
Invalid number of links. |
3 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
0 ms |
344 KB |
Output is correct |
2 |
Incorrect |
0 ms |
344 KB |
Invalid number of links. |
3 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
0 ms |
344 KB |
Output is correct |
2 |
Incorrect |
0 ms |
344 KB |
Invalid number of links. |
3 |
Halted |
0 ms |
0 KB |
- |