#include<bits/stdc++.h>
using namespace std;
const int maxn=500000+10;
int n;
vector<int>adj[maxn];
void vorod(){
cin>>n;
for(int i=0;i<n-1;i++){
int u,v;
cin>>u>>v;
adj[u].push_back(v);
adj[v].push_back(u);
}
}
vector<int>allv;
vector<pair<int,int>>res;
void dfs(int u,int par=-1){
if((int)adj[u].size()==1){
allv.push_back(u);
return ;
}
for(auto x:adj[u]){
if(x!=par){
dfs(x,u);
}
}
}
void pre(){
for(int i=1;i<=n;i++){
if((int)adj[i].size()>1){
dfs(i);
break;
}
}
int sz=allv.size();
for(int i=0;i<sz/2;i++){
res.push_back(make_pair(allv[i],allv[i+sz/2]));
}
if(sz&1){
res.push_back(make_pair(allv[0],allv.back()));
}
}
void khor(){
int sz=res.size();
cout<<sz<<"\n";
for(auto x:res){
cout<<x.first<<" "<<x.second<<"\n";
}
}
int main(){
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
//freopen("inp.txt","r",stdin);
vorod();
pre();
khor();
}
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 2 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 3 |
Correct |
4 ms |
12124 KB |
Output is correct |
| 4 |
Correct |
3 ms |
12196 KB |
Output is correct |
| 5 |
Correct |
3 ms |
12120 KB |
Output is correct |
| 6 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 7 |
Correct |
3 ms |
12120 KB |
Output is correct |
| 8 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 9 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 10 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 11 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 12 |
Correct |
3 ms |
12120 KB |
Output is correct |
| 13 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 14 |
Correct |
3 ms |
12120 KB |
Output is correct |
| 15 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 16 |
Correct |
3 ms |
12144 KB |
Output is correct |
| 17 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 18 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 19 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 20 |
Correct |
4 ms |
12204 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 2 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 3 |
Correct |
4 ms |
12124 KB |
Output is correct |
| 4 |
Correct |
3 ms |
12196 KB |
Output is correct |
| 5 |
Correct |
3 ms |
12120 KB |
Output is correct |
| 6 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 7 |
Correct |
3 ms |
12120 KB |
Output is correct |
| 8 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 9 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 10 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 11 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 12 |
Correct |
3 ms |
12120 KB |
Output is correct |
| 13 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 14 |
Correct |
3 ms |
12120 KB |
Output is correct |
| 15 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 16 |
Correct |
3 ms |
12144 KB |
Output is correct |
| 17 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 18 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 19 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 20 |
Correct |
4 ms |
12204 KB |
Output is correct |
| 21 |
Correct |
4 ms |
12124 KB |
Output is correct |
| 22 |
Correct |
4 ms |
12124 KB |
Output is correct |
| 23 |
Correct |
4 ms |
12124 KB |
Output is correct |
| 24 |
Correct |
4 ms |
12288 KB |
Output is correct |
| 25 |
Correct |
4 ms |
12124 KB |
Output is correct |
| 26 |
Correct |
4 ms |
12124 KB |
Output is correct |
| 27 |
Correct |
4 ms |
12120 KB |
Output is correct |
| 28 |
Correct |
4 ms |
12124 KB |
Output is correct |
| 29 |
Correct |
3 ms |
12120 KB |
Output is correct |
| 30 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 31 |
Correct |
4 ms |
12140 KB |
Output is correct |
| 32 |
Correct |
4 ms |
12376 KB |
Output is correct |
| 33 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 34 |
Correct |
3 ms |
12204 KB |
Output is correct |
| 35 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 36 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 37 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 38 |
Correct |
3 ms |
12120 KB |
Output is correct |
| 39 |
Correct |
3 ms |
12120 KB |
Output is correct |
| 40 |
Correct |
4 ms |
12124 KB |
Output is correct |
| 41 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 42 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 43 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 44 |
Correct |
4 ms |
12144 KB |
Output is correct |
| 45 |
Correct |
3 ms |
12196 KB |
Output is correct |
| 46 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 47 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 48 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 49 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 50 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 51 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 52 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 53 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 54 |
Correct |
3 ms |
12112 KB |
Output is correct |
| 55 |
Correct |
4 ms |
12124 KB |
Output is correct |
| 56 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 57 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 58 |
Correct |
4 ms |
12288 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 2 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 3 |
Correct |
4 ms |
12124 KB |
Output is correct |
| 4 |
Correct |
3 ms |
12196 KB |
Output is correct |
| 5 |
Correct |
3 ms |
12120 KB |
Output is correct |
| 6 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 7 |
Correct |
3 ms |
12120 KB |
Output is correct |
| 8 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 9 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 10 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 11 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 12 |
Correct |
3 ms |
12120 KB |
Output is correct |
| 13 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 14 |
Correct |
3 ms |
12120 KB |
Output is correct |
| 15 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 16 |
Correct |
3 ms |
12144 KB |
Output is correct |
| 17 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 18 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 19 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 20 |
Correct |
4 ms |
12204 KB |
Output is correct |
| 21 |
Correct |
4 ms |
12124 KB |
Output is correct |
| 22 |
Correct |
4 ms |
12124 KB |
Output is correct |
| 23 |
Correct |
4 ms |
12124 KB |
Output is correct |
| 24 |
Correct |
4 ms |
12288 KB |
Output is correct |
| 25 |
Correct |
4 ms |
12124 KB |
Output is correct |
| 26 |
Correct |
4 ms |
12124 KB |
Output is correct |
| 27 |
Correct |
4 ms |
12120 KB |
Output is correct |
| 28 |
Correct |
4 ms |
12124 KB |
Output is correct |
| 29 |
Correct |
3 ms |
12120 KB |
Output is correct |
| 30 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 31 |
Correct |
4 ms |
12140 KB |
Output is correct |
| 32 |
Correct |
4 ms |
12376 KB |
Output is correct |
| 33 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 34 |
Correct |
3 ms |
12204 KB |
Output is correct |
| 35 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 36 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 37 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 38 |
Correct |
3 ms |
12120 KB |
Output is correct |
| 39 |
Correct |
3 ms |
12120 KB |
Output is correct |
| 40 |
Correct |
4 ms |
12124 KB |
Output is correct |
| 41 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 42 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 43 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 44 |
Correct |
4 ms |
12144 KB |
Output is correct |
| 45 |
Correct |
3 ms |
12196 KB |
Output is correct |
| 46 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 47 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 48 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 49 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 50 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 51 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 52 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 53 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 54 |
Correct |
3 ms |
12112 KB |
Output is correct |
| 55 |
Correct |
4 ms |
12124 KB |
Output is correct |
| 56 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 57 |
Correct |
3 ms |
12124 KB |
Output is correct |
| 58 |
Correct |
4 ms |
12288 KB |
Output is correct |
| 59 |
Correct |
218 ms |
37136 KB |
Output is correct |
| 60 |
Correct |
247 ms |
40192 KB |
Output is correct |
| 61 |
Correct |
3 ms |
12120 KB |
Output is correct |
| 62 |
Correct |
4 ms |
12200 KB |
Output is correct |
| 63 |
Correct |
183 ms |
34896 KB |
Output is correct |
| 64 |
Correct |
5 ms |
12636 KB |
Output is correct |
| 65 |
Correct |
12 ms |
13944 KB |
Output is correct |
| 66 |
Correct |
75 ms |
27988 KB |
Output is correct |
| 67 |
Correct |
353 ms |
46872 KB |
Output is correct |
| 68 |
Correct |
382 ms |
47780 KB |
Output is correct |
| 69 |
Correct |
7 ms |
13144 KB |
Output is correct |
| 70 |
Correct |
60 ms |
22128 KB |
Output is correct |
| 71 |
Correct |
164 ms |
43804 KB |
Output is correct |
| 72 |
Correct |
181 ms |
42388 KB |
Output is correct |
| 73 |
Correct |
42 ms |
19408 KB |
Output is correct |
| 74 |
Correct |
256 ms |
38716 KB |
Output is correct |
| 75 |
Correct |
22 ms |
15496 KB |
Output is correct |
| 76 |
Correct |
178 ms |
43560 KB |
Output is correct |
| 77 |
Correct |
171 ms |
43568 KB |
Output is correct |
| 78 |
Correct |
21 ms |
15564 KB |
Output is correct |
| 79 |
Correct |
324 ms |
45180 KB |
Output is correct |
| 80 |
Correct |
4 ms |
12380 KB |
Output is correct |
| 81 |
Correct |
53 ms |
21724 KB |
Output is correct |
| 82 |
Correct |
209 ms |
41036 KB |
Output is correct |
| 83 |
Correct |
266 ms |
38744 KB |
Output is correct |
| 84 |
Correct |
284 ms |
38776 KB |
Output is correct |
| 85 |
Correct |
268 ms |
38888 KB |
Output is correct |
| 86 |
Correct |
256 ms |
40332 KB |
Output is correct |
| 87 |
Correct |
253 ms |
40004 KB |
Output is correct |
