#include<bits/stdc++.h>
using namespace std;
vector<int> ans;
vector<vector<int>> adj;
void dfs(int k,int pa){
if(adj[k].size()==1){
ans.push_back(k);
}
for(int j:adj[k]){
if(j==pa){
continue;
}
dfs(j,k);
}
}
int main(){
int n;cin>>n;
adj.resize(n);
for(int i=1;i<n;i++){
int a,b;cin>>a>>b;a--;b--;
adj[a].push_back(b);
adj[b].push_back(a);
}
dfs(0,0);
int m=ans.size();
for(int &j:ans){
j++;
}
cout<<(m+1)/2<<endl;
for(int i=0;i<m/2;i++){
cout<<ans[i]<<' '<<ans[i+m/2]<<endl;
}
if(m&1){
cout<<ans[0]<<' '<<ans[m-1]<<endl;
}
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
0 ms |
212 KB |
Output is correct |
2 |
Correct |
0 ms |
212 KB |
Output is correct |
3 |
Correct |
0 ms |
212 KB |
Output is correct |
4 |
Correct |
0 ms |
212 KB |
Output is correct |
5 |
Correct |
1 ms |
212 KB |
Output is correct |
6 |
Correct |
0 ms |
212 KB |
Output is correct |
7 |
Correct |
0 ms |
212 KB |
Output is correct |
8 |
Correct |
0 ms |
212 KB |
Output is correct |
9 |
Correct |
0 ms |
212 KB |
Output is correct |
10 |
Correct |
1 ms |
296 KB |
Output is correct |
11 |
Correct |
0 ms |
212 KB |
Output is correct |
12 |
Correct |
1 ms |
340 KB |
Output is correct |
13 |
Correct |
1 ms |
212 KB |
Output is correct |
14 |
Correct |
0 ms |
212 KB |
Output is correct |
15 |
Correct |
0 ms |
212 KB |
Output is correct |
16 |
Correct |
0 ms |
212 KB |
Output is correct |
17 |
Correct |
1 ms |
212 KB |
Output is correct |
18 |
Correct |
1 ms |
212 KB |
Output is correct |
19 |
Correct |
1 ms |
212 KB |
Output is correct |
20 |
Correct |
0 ms |
296 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
0 ms |
212 KB |
Output is correct |
2 |
Correct |
0 ms |
212 KB |
Output is correct |
3 |
Correct |
0 ms |
212 KB |
Output is correct |
4 |
Correct |
0 ms |
212 KB |
Output is correct |
5 |
Correct |
1 ms |
212 KB |
Output is correct |
6 |
Correct |
0 ms |
212 KB |
Output is correct |
7 |
Correct |
0 ms |
212 KB |
Output is correct |
8 |
Correct |
0 ms |
212 KB |
Output is correct |
9 |
Correct |
0 ms |
212 KB |
Output is correct |
10 |
Correct |
1 ms |
296 KB |
Output is correct |
11 |
Correct |
0 ms |
212 KB |
Output is correct |
12 |
Correct |
1 ms |
340 KB |
Output is correct |
13 |
Correct |
1 ms |
212 KB |
Output is correct |
14 |
Correct |
0 ms |
212 KB |
Output is correct |
15 |
Correct |
0 ms |
212 KB |
Output is correct |
16 |
Correct |
0 ms |
212 KB |
Output is correct |
17 |
Correct |
1 ms |
212 KB |
Output is correct |
18 |
Correct |
1 ms |
212 KB |
Output is correct |
19 |
Correct |
1 ms |
212 KB |
Output is correct |
20 |
Correct |
0 ms |
296 KB |
Output is correct |
21 |
Correct |
0 ms |
212 KB |
Output is correct |
22 |
Correct |
2 ms |
340 KB |
Output is correct |
23 |
Correct |
4 ms |
344 KB |
Output is correct |
24 |
Correct |
2 ms |
340 KB |
Output is correct |
25 |
Correct |
2 ms |
340 KB |
Output is correct |
26 |
Correct |
1 ms |
340 KB |
Output is correct |
27 |
Correct |
2 ms |
340 KB |
Output is correct |
28 |
Correct |
2 ms |
340 KB |
Output is correct |
29 |
Correct |
2 ms |
340 KB |
Output is correct |
30 |
Correct |
0 ms |
212 KB |
Output is correct |
31 |
Correct |
2 ms |
436 KB |
Output is correct |
32 |
Correct |
0 ms |
212 KB |
Output is correct |
33 |
Correct |
1 ms |
212 KB |
Output is correct |
34 |
Correct |
0 ms |
212 KB |
Output is correct |
35 |
Correct |
0 ms |
212 KB |
Output is correct |
36 |
Correct |
1 ms |
212 KB |
Output is correct |
37 |
Correct |
1 ms |
308 KB |
Output is correct |
38 |
Correct |
1 ms |
340 KB |
Output is correct |
39 |
Correct |
0 ms |
296 KB |
Output is correct |
40 |
Correct |
0 ms |
304 KB |
Output is correct |
41 |
Correct |
1 ms |
212 KB |
Output is correct |
42 |
Correct |
1 ms |
212 KB |
Output is correct |
43 |
Correct |
1 ms |
340 KB |
Output is correct |
44 |
Correct |
1 ms |
212 KB |
Output is correct |
45 |
Correct |
1 ms |
212 KB |
Output is correct |
46 |
Correct |
1 ms |
340 KB |
Output is correct |
47 |
Correct |
1 ms |
212 KB |
Output is correct |
48 |
Correct |
1 ms |
212 KB |
Output is correct |
49 |
Correct |
1 ms |
304 KB |
Output is correct |
50 |
Correct |
1 ms |
212 KB |
Output is correct |
51 |
Correct |
1 ms |
212 KB |
Output is correct |
52 |
Correct |
1 ms |
312 KB |
Output is correct |
53 |
Correct |
1 ms |
304 KB |
Output is correct |
54 |
Correct |
0 ms |
212 KB |
Output is correct |
55 |
Correct |
1 ms |
212 KB |
Output is correct |
56 |
Correct |
1 ms |
212 KB |
Output is correct |
57 |
Correct |
1 ms |
296 KB |
Output is correct |
58 |
Correct |
2 ms |
340 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
0 ms |
212 KB |
Output is correct |
2 |
Correct |
0 ms |
212 KB |
Output is correct |
3 |
Correct |
0 ms |
212 KB |
Output is correct |
4 |
Correct |
0 ms |
212 KB |
Output is correct |
5 |
Correct |
1 ms |
212 KB |
Output is correct |
6 |
Correct |
0 ms |
212 KB |
Output is correct |
7 |
Correct |
0 ms |
212 KB |
Output is correct |
8 |
Correct |
0 ms |
212 KB |
Output is correct |
9 |
Correct |
0 ms |
212 KB |
Output is correct |
10 |
Correct |
1 ms |
296 KB |
Output is correct |
11 |
Correct |
0 ms |
212 KB |
Output is correct |
12 |
Correct |
1 ms |
340 KB |
Output is correct |
13 |
Correct |
1 ms |
212 KB |
Output is correct |
14 |
Correct |
0 ms |
212 KB |
Output is correct |
15 |
Correct |
0 ms |
212 KB |
Output is correct |
16 |
Correct |
0 ms |
212 KB |
Output is correct |
17 |
Correct |
1 ms |
212 KB |
Output is correct |
18 |
Correct |
1 ms |
212 KB |
Output is correct |
19 |
Correct |
1 ms |
212 KB |
Output is correct |
20 |
Correct |
0 ms |
296 KB |
Output is correct |
21 |
Correct |
0 ms |
212 KB |
Output is correct |
22 |
Correct |
2 ms |
340 KB |
Output is correct |
23 |
Correct |
4 ms |
344 KB |
Output is correct |
24 |
Correct |
2 ms |
340 KB |
Output is correct |
25 |
Correct |
2 ms |
340 KB |
Output is correct |
26 |
Correct |
1 ms |
340 KB |
Output is correct |
27 |
Correct |
2 ms |
340 KB |
Output is correct |
28 |
Correct |
2 ms |
340 KB |
Output is correct |
29 |
Correct |
2 ms |
340 KB |
Output is correct |
30 |
Correct |
0 ms |
212 KB |
Output is correct |
31 |
Correct |
2 ms |
436 KB |
Output is correct |
32 |
Correct |
0 ms |
212 KB |
Output is correct |
33 |
Correct |
1 ms |
212 KB |
Output is correct |
34 |
Correct |
0 ms |
212 KB |
Output is correct |
35 |
Correct |
0 ms |
212 KB |
Output is correct |
36 |
Correct |
1 ms |
212 KB |
Output is correct |
37 |
Correct |
1 ms |
308 KB |
Output is correct |
38 |
Correct |
1 ms |
340 KB |
Output is correct |
39 |
Correct |
0 ms |
296 KB |
Output is correct |
40 |
Correct |
0 ms |
304 KB |
Output is correct |
41 |
Correct |
1 ms |
212 KB |
Output is correct |
42 |
Correct |
1 ms |
212 KB |
Output is correct |
43 |
Correct |
1 ms |
340 KB |
Output is correct |
44 |
Correct |
1 ms |
212 KB |
Output is correct |
45 |
Correct |
1 ms |
212 KB |
Output is correct |
46 |
Correct |
1 ms |
340 KB |
Output is correct |
47 |
Correct |
1 ms |
212 KB |
Output is correct |
48 |
Correct |
1 ms |
212 KB |
Output is correct |
49 |
Correct |
1 ms |
304 KB |
Output is correct |
50 |
Correct |
1 ms |
212 KB |
Output is correct |
51 |
Correct |
1 ms |
212 KB |
Output is correct |
52 |
Correct |
1 ms |
312 KB |
Output is correct |
53 |
Correct |
1 ms |
304 KB |
Output is correct |
54 |
Correct |
0 ms |
212 KB |
Output is correct |
55 |
Correct |
1 ms |
212 KB |
Output is correct |
56 |
Correct |
1 ms |
212 KB |
Output is correct |
57 |
Correct |
1 ms |
296 KB |
Output is correct |
58 |
Correct |
2 ms |
340 KB |
Output is correct |
59 |
Correct |
531 ms |
34840 KB |
Output is correct |
60 |
Correct |
613 ms |
38712 KB |
Output is correct |
61 |
Correct |
1 ms |
212 KB |
Output is correct |
62 |
Correct |
0 ms |
212 KB |
Output is correct |
63 |
Correct |
467 ms |
31248 KB |
Output is correct |
64 |
Correct |
3 ms |
724 KB |
Output is correct |
65 |
Correct |
14 ms |
2648 KB |
Output is correct |
66 |
Correct |
117 ms |
20320 KB |
Output is correct |
67 |
Correct |
510 ms |
46864 KB |
Output is correct |
68 |
Correct |
506 ms |
47572 KB |
Output is correct |
69 |
Correct |
15 ms |
1492 KB |
Output is correct |
70 |
Correct |
206 ms |
13184 KB |
Output is correct |
71 |
Correct |
600 ms |
41948 KB |
Output is correct |
72 |
Correct |
592 ms |
40684 KB |
Output is correct |
73 |
Correct |
145 ms |
10620 KB |
Output is correct |
74 |
Correct |
538 ms |
37572 KB |
Output is correct |
75 |
Correct |
62 ms |
4784 KB |
Output is correct |
76 |
Correct |
590 ms |
41560 KB |
Output is correct |
77 |
Correct |
651 ms |
41516 KB |
Output is correct |
78 |
Correct |
43 ms |
4780 KB |
Output is correct |
79 |
Correct |
479 ms |
45144 KB |
Output is correct |
80 |
Correct |
4 ms |
620 KB |
Output is correct |
81 |
Correct |
177 ms |
13484 KB |
Output is correct |
82 |
Correct |
601 ms |
39404 KB |
Output is correct |
83 |
Correct |
577 ms |
37572 KB |
Output is correct |
84 |
Correct |
576 ms |
37568 KB |
Output is correct |
85 |
Correct |
579 ms |
37660 KB |
Output is correct |
86 |
Correct |
603 ms |
38696 KB |
Output is correct |
87 |
Correct |
829 ms |
38660 KB |
Output is correct |