#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];
vector <pii> ans;
vector <int> leaf;
int root;
void dfs(int nw, int par){
if(adj[nw].size()==1) leaf.pb(nw);
for(auto nx : adj[nw]){
if(nx==par) continue;
dfs(nx, nw);
}
}
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);
}
for(int i=1; i<=n; i++){
if(adj[i].size()!=1) root = i;
}
dfs(root, 0);
int siz = leaf.size();
cout << (leaf.size()+1)/2 << '\n';
for(int i=0; i<(siz+1)/2; i++)
cout << leaf[i] << ' ' << leaf[i+siz/2] << '\n';
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
0 ms |
600 KB |
Output is correct |
2 |
Correct |
0 ms |
348 KB |
Output is correct |
3 |
Correct |
0 ms |
604 KB |
Output is correct |
4 |
Correct |
0 ms |
344 KB |
Output is correct |
5 |
Correct |
0 ms |
348 KB |
Output is correct |
6 |
Correct |
0 ms |
348 KB |
Output is correct |
7 |
Correct |
1 ms |
344 KB |
Output is correct |
8 |
Correct |
0 ms |
604 KB |
Output is correct |
9 |
Correct |
0 ms |
348 KB |
Output is correct |
10 |
Correct |
0 ms |
344 KB |
Output is correct |
11 |
Correct |
0 ms |
344 KB |
Output is correct |
12 |
Correct |
0 ms |
348 KB |
Output is correct |
13 |
Correct |
0 ms |
348 KB |
Output is correct |
14 |
Correct |
0 ms |
344 KB |
Output is correct |
15 |
Correct |
0 ms |
348 KB |
Output is correct |
16 |
Correct |
1 ms |
344 KB |
Output is correct |
17 |
Correct |
1 ms |
344 KB |
Output is correct |
18 |
Correct |
0 ms |
344 KB |
Output is correct |
19 |
Correct |
1 ms |
344 KB |
Output is correct |
20 |
Correct |
0 ms |
348 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
0 ms |
600 KB |
Output is correct |
2 |
Correct |
0 ms |
348 KB |
Output is correct |
3 |
Correct |
0 ms |
604 KB |
Output is correct |
4 |
Correct |
0 ms |
344 KB |
Output is correct |
5 |
Correct |
0 ms |
348 KB |
Output is correct |
6 |
Correct |
0 ms |
348 KB |
Output is correct |
7 |
Correct |
1 ms |
344 KB |
Output is correct |
8 |
Correct |
0 ms |
604 KB |
Output is correct |
9 |
Correct |
0 ms |
348 KB |
Output is correct |
10 |
Correct |
0 ms |
344 KB |
Output is correct |
11 |
Correct |
0 ms |
344 KB |
Output is correct |
12 |
Correct |
0 ms |
348 KB |
Output is correct |
13 |
Correct |
0 ms |
348 KB |
Output is correct |
14 |
Correct |
0 ms |
344 KB |
Output is correct |
15 |
Correct |
0 ms |
348 KB |
Output is correct |
16 |
Correct |
1 ms |
344 KB |
Output is correct |
17 |
Correct |
1 ms |
344 KB |
Output is correct |
18 |
Correct |
0 ms |
344 KB |
Output is correct |
19 |
Correct |
1 ms |
344 KB |
Output is correct |
20 |
Correct |
0 ms |
348 KB |
Output is correct |
21 |
Correct |
0 ms |
348 KB |
Output is correct |
22 |
Correct |
1 ms |
612 KB |
Output is correct |
23 |
Correct |
1 ms |
604 KB |
Output is correct |
24 |
Correct |
1 ms |
604 KB |
Output is correct |
25 |
Correct |
1 ms |
604 KB |
Output is correct |
26 |
Correct |
1 ms |
348 KB |
Output is correct |
27 |
Correct |
1 ms |
604 KB |
Output is correct |
28 |
Correct |
1 ms |
604 KB |
Output is correct |
29 |
Correct |
2 ms |
604 KB |
Output is correct |
30 |
Correct |
1 ms |
348 KB |
Output is correct |
31 |
Correct |
1 ms |
604 KB |
Output is correct |
32 |
Correct |
0 ms |
348 KB |
Output is correct |
33 |
Correct |
0 ms |
348 KB |
Output is correct |
34 |
Correct |
1 ms |
348 KB |
Output is correct |
35 |
Correct |
0 ms |
348 KB |
Output is correct |
36 |
Correct |
0 ms |
344 KB |
Output is correct |
37 |
Correct |
1 ms |
344 KB |
Output is correct |
38 |
Correct |
1 ms |
348 KB |
Output is correct |
39 |
Correct |
0 ms |
508 KB |
Output is correct |
40 |
Correct |
0 ms |
348 KB |
Output is correct |
41 |
Correct |
0 ms |
348 KB |
Output is correct |
42 |
Correct |
1 ms |
348 KB |
Output is correct |
43 |
Correct |
1 ms |
348 KB |
Output is correct |
44 |
Correct |
0 ms |
348 KB |
Output is correct |
45 |
Correct |
1 ms |
348 KB |
Output is correct |
46 |
Correct |
1 ms |
348 KB |
Output is correct |
47 |
Correct |
1 ms |
348 KB |
Output is correct |
48 |
Correct |
1 ms |
344 KB |
Output is correct |
49 |
Correct |
1 ms |
348 KB |
Output is correct |
50 |
Correct |
0 ms |
348 KB |
Output is correct |
51 |
Correct |
0 ms |
504 KB |
Output is correct |
52 |
Correct |
1 ms |
348 KB |
Output is correct |
53 |
Correct |
1 ms |
348 KB |
Output is correct |
54 |
Correct |
0 ms |
348 KB |
Output is correct |
55 |
Correct |
1 ms |
348 KB |
Output is correct |
56 |
Correct |
0 ms |
348 KB |
Output is correct |
57 |
Correct |
0 ms |
348 KB |
Output is correct |
58 |
Correct |
1 ms |
600 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
0 ms |
600 KB |
Output is correct |
2 |
Correct |
0 ms |
348 KB |
Output is correct |
3 |
Correct |
0 ms |
604 KB |
Output is correct |
4 |
Correct |
0 ms |
344 KB |
Output is correct |
5 |
Correct |
0 ms |
348 KB |
Output is correct |
6 |
Correct |
0 ms |
348 KB |
Output is correct |
7 |
Correct |
1 ms |
344 KB |
Output is correct |
8 |
Correct |
0 ms |
604 KB |
Output is correct |
9 |
Correct |
0 ms |
348 KB |
Output is correct |
10 |
Correct |
0 ms |
344 KB |
Output is correct |
11 |
Correct |
0 ms |
344 KB |
Output is correct |
12 |
Correct |
0 ms |
348 KB |
Output is correct |
13 |
Correct |
0 ms |
348 KB |
Output is correct |
14 |
Correct |
0 ms |
344 KB |
Output is correct |
15 |
Correct |
0 ms |
348 KB |
Output is correct |
16 |
Correct |
1 ms |
344 KB |
Output is correct |
17 |
Correct |
1 ms |
344 KB |
Output is correct |
18 |
Correct |
0 ms |
344 KB |
Output is correct |
19 |
Correct |
1 ms |
344 KB |
Output is correct |
20 |
Correct |
0 ms |
348 KB |
Output is correct |
21 |
Correct |
0 ms |
348 KB |
Output is correct |
22 |
Correct |
1 ms |
612 KB |
Output is correct |
23 |
Correct |
1 ms |
604 KB |
Output is correct |
24 |
Correct |
1 ms |
604 KB |
Output is correct |
25 |
Correct |
1 ms |
604 KB |
Output is correct |
26 |
Correct |
1 ms |
348 KB |
Output is correct |
27 |
Correct |
1 ms |
604 KB |
Output is correct |
28 |
Correct |
1 ms |
604 KB |
Output is correct |
29 |
Correct |
2 ms |
604 KB |
Output is correct |
30 |
Correct |
1 ms |
348 KB |
Output is correct |
31 |
Correct |
1 ms |
604 KB |
Output is correct |
32 |
Correct |
0 ms |
348 KB |
Output is correct |
33 |
Correct |
0 ms |
348 KB |
Output is correct |
34 |
Correct |
1 ms |
348 KB |
Output is correct |
35 |
Correct |
0 ms |
348 KB |
Output is correct |
36 |
Correct |
0 ms |
344 KB |
Output is correct |
37 |
Correct |
1 ms |
344 KB |
Output is correct |
38 |
Correct |
1 ms |
348 KB |
Output is correct |
39 |
Correct |
0 ms |
508 KB |
Output is correct |
40 |
Correct |
0 ms |
348 KB |
Output is correct |
41 |
Correct |
0 ms |
348 KB |
Output is correct |
42 |
Correct |
1 ms |
348 KB |
Output is correct |
43 |
Correct |
1 ms |
348 KB |
Output is correct |
44 |
Correct |
0 ms |
348 KB |
Output is correct |
45 |
Correct |
1 ms |
348 KB |
Output is correct |
46 |
Correct |
1 ms |
348 KB |
Output is correct |
47 |
Correct |
1 ms |
348 KB |
Output is correct |
48 |
Correct |
1 ms |
344 KB |
Output is correct |
49 |
Correct |
1 ms |
348 KB |
Output is correct |
50 |
Correct |
0 ms |
348 KB |
Output is correct |
51 |
Correct |
0 ms |
504 KB |
Output is correct |
52 |
Correct |
1 ms |
348 KB |
Output is correct |
53 |
Correct |
1 ms |
348 KB |
Output is correct |
54 |
Correct |
0 ms |
348 KB |
Output is correct |
55 |
Correct |
1 ms |
348 KB |
Output is correct |
56 |
Correct |
0 ms |
348 KB |
Output is correct |
57 |
Correct |
0 ms |
348 KB |
Output is correct |
58 |
Correct |
1 ms |
600 KB |
Output is correct |
59 |
Runtime error |
1 ms |
600 KB |
Execution killed with signal 11 |
60 |
Halted |
0 ms |
0 KB |
- |