| # |
Submission time |
Handle |
Problem |
Language |
Result |
Execution time |
Memory |
| 906224 |
2024-01-13T19:21:45 Z |
dsyz |
Network (BOI15_net) |
C++17 |
|
496 ms |
54456 KB |
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define MAXN (500005)
ll N, cnt = 0;
ll pre[MAXN];
vector<ll> v[MAXN];
bool leaf[MAXN];
void dfs(ll x,ll p){
pre[x] = cnt++;
ll children = 0;
for(auto u : v[x]){
if(u != p){
dfs(u,x);
children++;
}
}
if(children == 0){
leaf[x] = 1;
}
}
int main() {
ios_base::sync_with_stdio(false);cin.tie(0);
cin>>N;
for(ll i = 0;i < N - 1;i++){
ll a,b;
cin>>a>>b;
a--, b--;
v[a].push_back(b);
v[b].push_back(a);
}
dfs(0,-1);
deque<pair<ll,ll> > ans;
for(ll i = 0;i < N;i++){
if(i == 0 && v[0].size() == 1){ //technically the root node can also be a "leaf" if rooted differently
ans.push_back({pre[i],i});
}else if(leaf[i]){
ans.push_back({pre[i],i});
}
}
sort(ans.begin(),ans.end());
cout<<(ans.size() + 1) / 2<<'\n';
for(ll i = 0;i < ll((ans.size() + 1) / 2);i++){ //greedily optimal to pair front and middle (intution: at least one of the pair will have lca = root node)
cout<<ans[i].second + 1<<" "<<ans[i + (ans.size() / 2)].second + 1<<'\n';
}
}
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 2 |
Correct |
4 ms |
12648 KB |
Output is correct |
| 3 |
Correct |
3 ms |
12708 KB |
Output is correct |
| 4 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 5 |
Correct |
4 ms |
12636 KB |
Output is correct |
| 6 |
Correct |
4 ms |
12636 KB |
Output is correct |
| 7 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 8 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 9 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 10 |
Correct |
3 ms |
12776 KB |
Output is correct |
| 11 |
Correct |
5 ms |
12636 KB |
Output is correct |
| 12 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 13 |
Correct |
3 ms |
12776 KB |
Output is correct |
| 14 |
Correct |
4 ms |
12636 KB |
Output is correct |
| 15 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 16 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 17 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 18 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 19 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 20 |
Correct |
3 ms |
12776 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 2 |
Correct |
4 ms |
12648 KB |
Output is correct |
| 3 |
Correct |
3 ms |
12708 KB |
Output is correct |
| 4 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 5 |
Correct |
4 ms |
12636 KB |
Output is correct |
| 6 |
Correct |
4 ms |
12636 KB |
Output is correct |
| 7 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 8 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 9 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 10 |
Correct |
3 ms |
12776 KB |
Output is correct |
| 11 |
Correct |
5 ms |
12636 KB |
Output is correct |
| 12 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 13 |
Correct |
3 ms |
12776 KB |
Output is correct |
| 14 |
Correct |
4 ms |
12636 KB |
Output is correct |
| 15 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 16 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 17 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 18 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 19 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 20 |
Correct |
3 ms |
12776 KB |
Output is correct |
| 21 |
Correct |
5 ms |
12636 KB |
Output is correct |
| 22 |
Correct |
5 ms |
13144 KB |
Output is correct |
| 23 |
Correct |
4 ms |
12892 KB |
Output is correct |
| 24 |
Correct |
4 ms |
12892 KB |
Output is correct |
| 25 |
Correct |
4 ms |
13144 KB |
Output is correct |
| 26 |
Correct |
4 ms |
12636 KB |
Output is correct |
| 27 |
Correct |
4 ms |
12848 KB |
Output is correct |
| 28 |
Correct |
4 ms |
12904 KB |
Output is correct |
| 29 |
Correct |
4 ms |
12636 KB |
Output is correct |
| 30 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 31 |
Correct |
4 ms |
12892 KB |
Output is correct |
| 32 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 33 |
Correct |
4 ms |
12636 KB |
Output is correct |
| 34 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 35 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 36 |
Correct |
4 ms |
12636 KB |
Output is correct |
| 37 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 38 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 39 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 40 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 41 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 42 |
Correct |
4 ms |
12636 KB |
Output is correct |
| 43 |
Correct |
4 ms |
12636 KB |
Output is correct |
| 44 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 45 |
Correct |
4 ms |
12636 KB |
Output is correct |
| 46 |
Correct |
6 ms |
13144 KB |
Output is correct |
| 47 |
Correct |
4 ms |
12636 KB |
Output is correct |
| 48 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 49 |
Correct |
4 ms |
12636 KB |
Output is correct |
| 50 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 51 |
Correct |
3 ms |
12780 KB |
Output is correct |
| 52 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 53 |
Correct |
4 ms |
12888 KB |
Output is correct |
| 54 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 55 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 56 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 57 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 58 |
Correct |
4 ms |
12892 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 2 |
Correct |
4 ms |
12648 KB |
Output is correct |
| 3 |
Correct |
3 ms |
12708 KB |
Output is correct |
| 4 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 5 |
Correct |
4 ms |
12636 KB |
Output is correct |
| 6 |
Correct |
4 ms |
12636 KB |
Output is correct |
| 7 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 8 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 9 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 10 |
Correct |
3 ms |
12776 KB |
Output is correct |
| 11 |
Correct |
5 ms |
12636 KB |
Output is correct |
| 12 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 13 |
Correct |
3 ms |
12776 KB |
Output is correct |
| 14 |
Correct |
4 ms |
12636 KB |
Output is correct |
| 15 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 16 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 17 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 18 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 19 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 20 |
Correct |
3 ms |
12776 KB |
Output is correct |
| 21 |
Correct |
5 ms |
12636 KB |
Output is correct |
| 22 |
Correct |
5 ms |
13144 KB |
Output is correct |
| 23 |
Correct |
4 ms |
12892 KB |
Output is correct |
| 24 |
Correct |
4 ms |
12892 KB |
Output is correct |
| 25 |
Correct |
4 ms |
13144 KB |
Output is correct |
| 26 |
Correct |
4 ms |
12636 KB |
Output is correct |
| 27 |
Correct |
4 ms |
12848 KB |
Output is correct |
| 28 |
Correct |
4 ms |
12904 KB |
Output is correct |
| 29 |
Correct |
4 ms |
12636 KB |
Output is correct |
| 30 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 31 |
Correct |
4 ms |
12892 KB |
Output is correct |
| 32 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 33 |
Correct |
4 ms |
12636 KB |
Output is correct |
| 34 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 35 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 36 |
Correct |
4 ms |
12636 KB |
Output is correct |
| 37 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 38 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 39 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 40 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 41 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 42 |
Correct |
4 ms |
12636 KB |
Output is correct |
| 43 |
Correct |
4 ms |
12636 KB |
Output is correct |
| 44 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 45 |
Correct |
4 ms |
12636 KB |
Output is correct |
| 46 |
Correct |
6 ms |
13144 KB |
Output is correct |
| 47 |
Correct |
4 ms |
12636 KB |
Output is correct |
| 48 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 49 |
Correct |
4 ms |
12636 KB |
Output is correct |
| 50 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 51 |
Correct |
3 ms |
12780 KB |
Output is correct |
| 52 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 53 |
Correct |
4 ms |
12888 KB |
Output is correct |
| 54 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 55 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 56 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 57 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 58 |
Correct |
4 ms |
12892 KB |
Output is correct |
| 59 |
Correct |
394 ms |
47164 KB |
Output is correct |
| 60 |
Correct |
401 ms |
50516 KB |
Output is correct |
| 61 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 62 |
Correct |
3 ms |
12636 KB |
Output is correct |
| 63 |
Correct |
254 ms |
42952 KB |
Output is correct |
| 64 |
Correct |
5 ms |
13148 KB |
Output is correct |
| 65 |
Correct |
12 ms |
14684 KB |
Output is correct |
| 66 |
Correct |
73 ms |
30808 KB |
Output is correct |
| 67 |
Correct |
496 ms |
51284 KB |
Output is correct |
| 68 |
Correct |
477 ms |
53328 KB |
Output is correct |
| 69 |
Correct |
8 ms |
13660 KB |
Output is correct |
| 70 |
Correct |
72 ms |
26180 KB |
Output is correct |
| 71 |
Correct |
274 ms |
54456 KB |
Output is correct |
| 72 |
Correct |
289 ms |
52408 KB |
Output is correct |
| 73 |
Correct |
64 ms |
23364 KB |
Output is correct |
| 74 |
Correct |
396 ms |
47592 KB |
Output is correct |
| 75 |
Correct |
25 ms |
18772 KB |
Output is correct |
| 76 |
Correct |
301 ms |
53756 KB |
Output is correct |
| 77 |
Correct |
290 ms |
54096 KB |
Output is correct |
| 78 |
Correct |
23 ms |
18268 KB |
Output is correct |
| 79 |
Correct |
457 ms |
49752 KB |
Output is correct |
| 80 |
Correct |
4 ms |
12892 KB |
Output is correct |
| 81 |
Correct |
87 ms |
26224 KB |
Output is correct |
| 82 |
Correct |
347 ms |
50676 KB |
Output is correct |
| 83 |
Correct |
397 ms |
47696 KB |
Output is correct |
| 84 |
Correct |
420 ms |
47640 KB |
Output is correct |
| 85 |
Correct |
410 ms |
47652 KB |
Output is correct |
| 86 |
Correct |
382 ms |
50516 KB |
Output is correct |
| 87 |
Correct |
368 ms |
50516 KB |
Output is correct |
