#include <bits/stdc++.h>
#define int int64_t
using namespace std;
vector<vector<int>>graph;
vector<int>dist;
vector<int>leaf;
void dfs(int v, int p){
dist[v] = dist[p] + 1;
if(graph[v].size() == 1) leaf.push_back(v);
for(auto u: graph[v]){
if(u != p) dfs(u, v);
}
}
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int n; cin>>n;
graph.assign(n, vector<int>());
dist.assign(n, -1);
for(int i = 0; i<n-1; ++i){
int a, b; cin>>a>>b;
--a; --b;
graph[a].push_back(b);
graph[b].push_back(a);
}
dfs(0, 0);
int m = leaf.size();
/*
for(auto u: leaf) cout<<u<<" ";
cout<<endl;
for(auto u: dist) cout<<u<<" ";
cout<<endl;
*/
vector<pair<int, int>>fred;
for(auto u: leaf){
fred.push_back({dist[u], u});
}
sort(fred.begin(), fred.end());
/*
for(auto [x, y]: fred) cout<<y<<" ";
cout<<endl;
*/
cout<<(m+1)/2<<'\n';
for(int i = 0; i<m/2; ++i){
cout<<leaf[i]+1<<" "<<leaf[m/2+i]+1<<'\n';
}
if(leaf.size()%2) cout<<leaf[m/2]+1<<" "<<leaf[m-1]+1<<'\n';
//cout<<'\n';
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
0 ms |
308 KB |
Output is correct |
2 |
Correct |
0 ms |
204 KB |
Output is correct |
3 |
Correct |
1 ms |
204 KB |
Output is correct |
4 |
Correct |
1 ms |
312 KB |
Output is correct |
5 |
Correct |
0 ms |
204 KB |
Output is correct |
6 |
Correct |
0 ms |
204 KB |
Output is correct |
7 |
Correct |
0 ms |
204 KB |
Output is correct |
8 |
Correct |
0 ms |
204 KB |
Output is correct |
9 |
Correct |
0 ms |
204 KB |
Output is correct |
10 |
Correct |
1 ms |
204 KB |
Output is correct |
11 |
Correct |
0 ms |
204 KB |
Output is correct |
12 |
Correct |
0 ms |
204 KB |
Output is correct |
13 |
Correct |
1 ms |
204 KB |
Output is correct |
14 |
Correct |
1 ms |
204 KB |
Output is correct |
15 |
Correct |
1 ms |
204 KB |
Output is correct |
16 |
Correct |
0 ms |
204 KB |
Output is correct |
17 |
Correct |
1 ms |
204 KB |
Output is correct |
18 |
Correct |
0 ms |
204 KB |
Output is correct |
19 |
Correct |
1 ms |
204 KB |
Output is correct |
20 |
Correct |
0 ms |
204 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
0 ms |
308 KB |
Output is correct |
2 |
Correct |
0 ms |
204 KB |
Output is correct |
3 |
Correct |
1 ms |
204 KB |
Output is correct |
4 |
Correct |
1 ms |
312 KB |
Output is correct |
5 |
Correct |
0 ms |
204 KB |
Output is correct |
6 |
Correct |
0 ms |
204 KB |
Output is correct |
7 |
Correct |
0 ms |
204 KB |
Output is correct |
8 |
Correct |
0 ms |
204 KB |
Output is correct |
9 |
Correct |
0 ms |
204 KB |
Output is correct |
10 |
Correct |
1 ms |
204 KB |
Output is correct |
11 |
Correct |
0 ms |
204 KB |
Output is correct |
12 |
Correct |
0 ms |
204 KB |
Output is correct |
13 |
Correct |
1 ms |
204 KB |
Output is correct |
14 |
Correct |
1 ms |
204 KB |
Output is correct |
15 |
Correct |
1 ms |
204 KB |
Output is correct |
16 |
Correct |
0 ms |
204 KB |
Output is correct |
17 |
Correct |
1 ms |
204 KB |
Output is correct |
18 |
Correct |
0 ms |
204 KB |
Output is correct |
19 |
Correct |
1 ms |
204 KB |
Output is correct |
20 |
Correct |
0 ms |
204 KB |
Output is correct |
21 |
Correct |
1 ms |
204 KB |
Output is correct |
22 |
Correct |
2 ms |
460 KB |
Output is correct |
23 |
Correct |
1 ms |
460 KB |
Output is correct |
24 |
Correct |
1 ms |
460 KB |
Output is correct |
25 |
Correct |
1 ms |
460 KB |
Output is correct |
26 |
Correct |
2 ms |
460 KB |
Output is correct |
27 |
Correct |
1 ms |
460 KB |
Output is correct |
28 |
Correct |
1 ms |
460 KB |
Output is correct |
29 |
Correct |
1 ms |
412 KB |
Output is correct |
30 |
Correct |
0 ms |
204 KB |
Output is correct |
31 |
Correct |
2 ms |
460 KB |
Output is correct |
32 |
Correct |
0 ms |
204 KB |
Output is correct |
33 |
Correct |
0 ms |
312 KB |
Output is correct |
34 |
Correct |
0 ms |
204 KB |
Output is correct |
35 |
Correct |
0 ms |
204 KB |
Output is correct |
36 |
Correct |
1 ms |
204 KB |
Output is correct |
37 |
Correct |
1 ms |
332 KB |
Output is correct |
38 |
Correct |
1 ms |
332 KB |
Output is correct |
39 |
Correct |
1 ms |
204 KB |
Output is correct |
40 |
Correct |
1 ms |
204 KB |
Output is correct |
41 |
Correct |
1 ms |
204 KB |
Output is correct |
42 |
Correct |
1 ms |
332 KB |
Output is correct |
43 |
Correct |
1 ms |
332 KB |
Output is correct |
44 |
Correct |
1 ms |
312 KB |
Output is correct |
45 |
Correct |
1 ms |
332 KB |
Output is correct |
46 |
Correct |
1 ms |
332 KB |
Output is correct |
47 |
Correct |
1 ms |
204 KB |
Output is correct |
48 |
Correct |
1 ms |
332 KB |
Output is correct |
49 |
Correct |
1 ms |
344 KB |
Output is correct |
50 |
Correct |
1 ms |
312 KB |
Output is correct |
51 |
Correct |
1 ms |
204 KB |
Output is correct |
52 |
Correct |
1 ms |
332 KB |
Output is correct |
53 |
Correct |
1 ms |
312 KB |
Output is correct |
54 |
Correct |
0 ms |
204 KB |
Output is correct |
55 |
Correct |
1 ms |
332 KB |
Output is correct |
56 |
Correct |
1 ms |
204 KB |
Output is correct |
57 |
Correct |
1 ms |
332 KB |
Output is correct |
58 |
Correct |
1 ms |
448 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
0 ms |
308 KB |
Output is correct |
2 |
Correct |
0 ms |
204 KB |
Output is correct |
3 |
Correct |
1 ms |
204 KB |
Output is correct |
4 |
Correct |
1 ms |
312 KB |
Output is correct |
5 |
Correct |
0 ms |
204 KB |
Output is correct |
6 |
Correct |
0 ms |
204 KB |
Output is correct |
7 |
Correct |
0 ms |
204 KB |
Output is correct |
8 |
Correct |
0 ms |
204 KB |
Output is correct |
9 |
Correct |
0 ms |
204 KB |
Output is correct |
10 |
Correct |
1 ms |
204 KB |
Output is correct |
11 |
Correct |
0 ms |
204 KB |
Output is correct |
12 |
Correct |
0 ms |
204 KB |
Output is correct |
13 |
Correct |
1 ms |
204 KB |
Output is correct |
14 |
Correct |
1 ms |
204 KB |
Output is correct |
15 |
Correct |
1 ms |
204 KB |
Output is correct |
16 |
Correct |
0 ms |
204 KB |
Output is correct |
17 |
Correct |
1 ms |
204 KB |
Output is correct |
18 |
Correct |
0 ms |
204 KB |
Output is correct |
19 |
Correct |
1 ms |
204 KB |
Output is correct |
20 |
Correct |
0 ms |
204 KB |
Output is correct |
21 |
Correct |
1 ms |
204 KB |
Output is correct |
22 |
Correct |
2 ms |
460 KB |
Output is correct |
23 |
Correct |
1 ms |
460 KB |
Output is correct |
24 |
Correct |
1 ms |
460 KB |
Output is correct |
25 |
Correct |
1 ms |
460 KB |
Output is correct |
26 |
Correct |
2 ms |
460 KB |
Output is correct |
27 |
Correct |
1 ms |
460 KB |
Output is correct |
28 |
Correct |
1 ms |
460 KB |
Output is correct |
29 |
Correct |
1 ms |
412 KB |
Output is correct |
30 |
Correct |
0 ms |
204 KB |
Output is correct |
31 |
Correct |
2 ms |
460 KB |
Output is correct |
32 |
Correct |
0 ms |
204 KB |
Output is correct |
33 |
Correct |
0 ms |
312 KB |
Output is correct |
34 |
Correct |
0 ms |
204 KB |
Output is correct |
35 |
Correct |
0 ms |
204 KB |
Output is correct |
36 |
Correct |
1 ms |
204 KB |
Output is correct |
37 |
Correct |
1 ms |
332 KB |
Output is correct |
38 |
Correct |
1 ms |
332 KB |
Output is correct |
39 |
Correct |
1 ms |
204 KB |
Output is correct |
40 |
Correct |
1 ms |
204 KB |
Output is correct |
41 |
Correct |
1 ms |
204 KB |
Output is correct |
42 |
Correct |
1 ms |
332 KB |
Output is correct |
43 |
Correct |
1 ms |
332 KB |
Output is correct |
44 |
Correct |
1 ms |
312 KB |
Output is correct |
45 |
Correct |
1 ms |
332 KB |
Output is correct |
46 |
Correct |
1 ms |
332 KB |
Output is correct |
47 |
Correct |
1 ms |
204 KB |
Output is correct |
48 |
Correct |
1 ms |
332 KB |
Output is correct |
49 |
Correct |
1 ms |
344 KB |
Output is correct |
50 |
Correct |
1 ms |
312 KB |
Output is correct |
51 |
Correct |
1 ms |
204 KB |
Output is correct |
52 |
Correct |
1 ms |
332 KB |
Output is correct |
53 |
Correct |
1 ms |
312 KB |
Output is correct |
54 |
Correct |
0 ms |
204 KB |
Output is correct |
55 |
Correct |
1 ms |
332 KB |
Output is correct |
56 |
Correct |
1 ms |
204 KB |
Output is correct |
57 |
Correct |
1 ms |
332 KB |
Output is correct |
58 |
Correct |
1 ms |
448 KB |
Output is correct |
59 |
Correct |
455 ms |
49092 KB |
Output is correct |
60 |
Correct |
546 ms |
53184 KB |
Output is correct |
61 |
Correct |
1 ms |
204 KB |
Output is correct |
62 |
Correct |
1 ms |
204 KB |
Output is correct |
63 |
Correct |
404 ms |
43692 KB |
Output is correct |
64 |
Correct |
2 ms |
844 KB |
Output is correct |
65 |
Correct |
11 ms |
3020 KB |
Output is correct |
66 |
Correct |
158 ms |
21728 KB |
Output is correct |
67 |
Correct |
516 ms |
50808 KB |
Output is correct |
68 |
Correct |
540 ms |
53184 KB |
Output is correct |
69 |
Correct |
8 ms |
1996 KB |
Output is correct |
70 |
Correct |
116 ms |
18888 KB |
Output is correct |
71 |
Correct |
428 ms |
57500 KB |
Output is correct |
72 |
Correct |
410 ms |
55344 KB |
Output is correct |
73 |
Correct |
129 ms |
14252 KB |
Output is correct |
74 |
Correct |
513 ms |
49028 KB |
Output is correct |
75 |
Correct |
43 ms |
6460 KB |
Output is correct |
76 |
Correct |
409 ms |
56768 KB |
Output is correct |
77 |
Correct |
419 ms |
57228 KB |
Output is correct |
78 |
Correct |
28 ms |
5832 KB |
Output is correct |
79 |
Correct |
518 ms |
49116 KB |
Output is correct |
80 |
Correct |
3 ms |
716 KB |
Output is correct |
81 |
Correct |
142 ms |
18056 KB |
Output is correct |
82 |
Correct |
503 ms |
52936 KB |
Output is correct |
83 |
Correct |
555 ms |
48944 KB |
Output is correct |
84 |
Correct |
522 ms |
48944 KB |
Output is correct |
85 |
Correct |
514 ms |
49000 KB |
Output is correct |
86 |
Correct |
531 ms |
53204 KB |
Output is correct |
87 |
Correct |
519 ms |
53332 KB |
Output is correct |