/*
Editor: Abdelrahman Hossam
Nickname: Blobo2_Blobo2
IOI next year isA :)
*/
//#pragma GCC optimize ("O3")
//#pragma GCC optimize ("unroll-loops")
#include<bits/stdc++.h>
using namespace std;
#define int long long
#define endl "\n"
#define all(v) v.begin(),v.end()
#define gen(arr,n,nxt) generate(arr,arr+n,nxt)
#define Blobo2_el_gamded_gedan_elly_3ayz_yro7_IOI_w_3ayz_yakol_jilaty ios_base::sync_with_stdio(false);cin.tie(0);
const int mo=1e9+7;
int nxt(){int x;cin>>x;return x;}
bool vis[500001];
vector<int>v;
void dfs(int &cnt,vector<int>adj[],int u=0){
vis[u]=1;
if(adj[u].size()==1){
cnt++;
v.push_back(u);
}
for(auto c:adj[u]){
if(!vis[c]){
dfs(cnt,adj,c);
}
}
}
signed main(){
Blobo2_el_gamded_gedan_elly_3ayz_yro7_IOI_w_3ayz_yakol_jilaty
int n=nxt();
vector<int>adj[n];
for(int i=0;i<n-1;i++){
int x=nxt()-1,y=nxt()-1;
adj[x].push_back(y);
adj[y].push_back(x);
}
int cnt=0;
dfs(cnt,adj);
cout<<(cnt+1)/2<<endl;
if(cnt%2==0){
for(int i=0;i<v.size()/2;i++)
cout<<v[i]+1<<' '<<v[i+(cnt/2)]+1<<endl;
}
else{
for(int i=0;i<v.size()/2;i++)
cout<<v[i]+1<<' '<<v[i+(cnt/2+1)]+1<<endl;
cout<<v[cnt/2]+1<<' ';
int p = adj[v.back()][0];
for(int i=0;i<n;i++){
if(i!=p&&i!=v.back()){
cout<<i+1<<endl;
break;
}
}
}
return 0;
}
Compilation message
net.cpp: In function 'int main()':
net.cpp:45:22: 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=0;i<v.size()/2;i++)
| ~^~~~~~~~~~~
net.cpp:49:22: 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]
49 | for(int i=0;i<v.size()/2;i++)
| ~^~~~~~~~~~~
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
204 KB |
Output is correct |
2 |
Correct |
1 ms |
204 KB |
Output is correct |
3 |
Correct |
1 ms |
204 KB |
Output is correct |
4 |
Correct |
1 ms |
204 KB |
Output is correct |
5 |
Correct |
1 ms |
204 KB |
Output is correct |
6 |
Correct |
1 ms |
204 KB |
Output is correct |
7 |
Correct |
1 ms |
204 KB |
Output is correct |
8 |
Correct |
1 ms |
204 KB |
Output is correct |
9 |
Correct |
1 ms |
204 KB |
Output is correct |
10 |
Correct |
1 ms |
204 KB |
Output is correct |
11 |
Correct |
1 ms |
204 KB |
Output is correct |
12 |
Correct |
1 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 |
1 ms |
316 KB |
Output is correct |
17 |
Correct |
1 ms |
204 KB |
Output is correct |
18 |
Correct |
1 ms |
204 KB |
Output is correct |
19 |
Correct |
1 ms |
204 KB |
Output is correct |
20 |
Correct |
1 ms |
204 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
204 KB |
Output is correct |
2 |
Correct |
1 ms |
204 KB |
Output is correct |
3 |
Correct |
1 ms |
204 KB |
Output is correct |
4 |
Correct |
1 ms |
204 KB |
Output is correct |
5 |
Correct |
1 ms |
204 KB |
Output is correct |
6 |
Correct |
1 ms |
204 KB |
Output is correct |
7 |
Correct |
1 ms |
204 KB |
Output is correct |
8 |
Correct |
1 ms |
204 KB |
Output is correct |
9 |
Correct |
1 ms |
204 KB |
Output is correct |
10 |
Correct |
1 ms |
204 KB |
Output is correct |
11 |
Correct |
1 ms |
204 KB |
Output is correct |
12 |
Correct |
1 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 |
1 ms |
316 KB |
Output is correct |
17 |
Correct |
1 ms |
204 KB |
Output is correct |
18 |
Correct |
1 ms |
204 KB |
Output is correct |
19 |
Correct |
1 ms |
204 KB |
Output is correct |
20 |
Correct |
1 ms |
204 KB |
Output is correct |
21 |
Correct |
1 ms |
204 KB |
Output is correct |
22 |
Correct |
1 ms |
460 KB |
Output is correct |
23 |
Correct |
1 ms |
460 KB |
Output is correct |
24 |
Correct |
2 ms |
460 KB |
Output is correct |
25 |
Correct |
2 ms |
460 KB |
Output is correct |
26 |
Correct |
2 ms |
328 KB |
Output is correct |
27 |
Correct |
2 ms |
460 KB |
Output is correct |
28 |
Correct |
2 ms |
460 KB |
Output is correct |
29 |
Correct |
2 ms |
332 KB |
Output is correct |
30 |
Correct |
1 ms |
204 KB |
Output is correct |
31 |
Correct |
1 ms |
460 KB |
Output is correct |
32 |
Correct |
1 ms |
204 KB |
Output is correct |
33 |
Correct |
1 ms |
324 KB |
Output is correct |
34 |
Correct |
1 ms |
316 KB |
Output is correct |
35 |
Correct |
1 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 |
316 KB |
Output is correct |
41 |
Correct |
1 ms |
332 KB |
Output is correct |
42 |
Correct |
1 ms |
332 KB |
Output is correct |
43 |
Correct |
1 ms |
324 KB |
Output is correct |
44 |
Correct |
1 ms |
204 KB |
Output is correct |
45 |
Correct |
3 ms |
332 KB |
Output is correct |
46 |
Correct |
1 ms |
332 KB |
Output is correct |
47 |
Correct |
1 ms |
320 KB |
Output is correct |
48 |
Correct |
1 ms |
332 KB |
Output is correct |
49 |
Correct |
1 ms |
332 KB |
Output is correct |
50 |
Correct |
1 ms |
204 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 |
332 KB |
Output is correct |
54 |
Correct |
1 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 |
2 ms |
504 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
204 KB |
Output is correct |
2 |
Correct |
1 ms |
204 KB |
Output is correct |
3 |
Correct |
1 ms |
204 KB |
Output is correct |
4 |
Correct |
1 ms |
204 KB |
Output is correct |
5 |
Correct |
1 ms |
204 KB |
Output is correct |
6 |
Correct |
1 ms |
204 KB |
Output is correct |
7 |
Correct |
1 ms |
204 KB |
Output is correct |
8 |
Correct |
1 ms |
204 KB |
Output is correct |
9 |
Correct |
1 ms |
204 KB |
Output is correct |
10 |
Correct |
1 ms |
204 KB |
Output is correct |
11 |
Correct |
1 ms |
204 KB |
Output is correct |
12 |
Correct |
1 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 |
1 ms |
316 KB |
Output is correct |
17 |
Correct |
1 ms |
204 KB |
Output is correct |
18 |
Correct |
1 ms |
204 KB |
Output is correct |
19 |
Correct |
1 ms |
204 KB |
Output is correct |
20 |
Correct |
1 ms |
204 KB |
Output is correct |
21 |
Correct |
1 ms |
204 KB |
Output is correct |
22 |
Correct |
1 ms |
460 KB |
Output is correct |
23 |
Correct |
1 ms |
460 KB |
Output is correct |
24 |
Correct |
2 ms |
460 KB |
Output is correct |
25 |
Correct |
2 ms |
460 KB |
Output is correct |
26 |
Correct |
2 ms |
328 KB |
Output is correct |
27 |
Correct |
2 ms |
460 KB |
Output is correct |
28 |
Correct |
2 ms |
460 KB |
Output is correct |
29 |
Correct |
2 ms |
332 KB |
Output is correct |
30 |
Correct |
1 ms |
204 KB |
Output is correct |
31 |
Correct |
1 ms |
460 KB |
Output is correct |
32 |
Correct |
1 ms |
204 KB |
Output is correct |
33 |
Correct |
1 ms |
324 KB |
Output is correct |
34 |
Correct |
1 ms |
316 KB |
Output is correct |
35 |
Correct |
1 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 |
316 KB |
Output is correct |
41 |
Correct |
1 ms |
332 KB |
Output is correct |
42 |
Correct |
1 ms |
332 KB |
Output is correct |
43 |
Correct |
1 ms |
324 KB |
Output is correct |
44 |
Correct |
1 ms |
204 KB |
Output is correct |
45 |
Correct |
3 ms |
332 KB |
Output is correct |
46 |
Correct |
1 ms |
332 KB |
Output is correct |
47 |
Correct |
1 ms |
320 KB |
Output is correct |
48 |
Correct |
1 ms |
332 KB |
Output is correct |
49 |
Correct |
1 ms |
332 KB |
Output is correct |
50 |
Correct |
1 ms |
204 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 |
332 KB |
Output is correct |
54 |
Correct |
1 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 |
2 ms |
504 KB |
Output is correct |
59 |
Correct |
498 ms |
39828 KB |
Output is correct |
60 |
Correct |
599 ms |
43948 KB |
Output is correct |
61 |
Correct |
1 ms |
204 KB |
Output is correct |
62 |
Correct |
1 ms |
204 KB |
Output is correct |
63 |
Correct |
399 ms |
34812 KB |
Output is correct |
64 |
Correct |
3 ms |
844 KB |
Output is correct |
65 |
Correct |
13 ms |
3104 KB |
Output is correct |
66 |
Correct |
172 ms |
23220 KB |
Output is correct |
67 |
Correct |
595 ms |
51660 KB |
Output is correct |
68 |
Correct |
620 ms |
53272 KB |
Output is correct |
69 |
Correct |
7 ms |
1740 KB |
Output is correct |
70 |
Correct |
106 ms |
15476 KB |
Output is correct |
71 |
Correct |
377 ms |
46236 KB |
Output is correct |
72 |
Correct |
445 ms |
44848 KB |
Output is correct |
73 |
Correct |
94 ms |
11672 KB |
Output is correct |
74 |
Correct |
546 ms |
41728 KB |
Output is correct |
75 |
Correct |
26 ms |
5188 KB |
Output is correct |
76 |
Correct |
367 ms |
45840 KB |
Output is correct |
77 |
Correct |
372 ms |
46092 KB |
Output is correct |
78 |
Correct |
28 ms |
5444 KB |
Output is correct |
79 |
Correct |
638 ms |
49328 KB |
Output is correct |
80 |
Correct |
2 ms |
588 KB |
Output is correct |
81 |
Correct |
120 ms |
14892 KB |
Output is correct |
82 |
Correct |
454 ms |
43756 KB |
Output is correct |
83 |
Correct |
518 ms |
41668 KB |
Output is correct |
84 |
Correct |
528 ms |
41636 KB |
Output is correct |
85 |
Correct |
541 ms |
41632 KB |
Output is correct |
86 |
Correct |
532 ms |
43820 KB |
Output is correct |
87 |
Correct |
549 ms |
44000 KB |
Output is correct |