#include <bits/stdc++.h>
#define FAST ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);cerr.tie(0)
#define mp make_pair
#define xx first
#define yy second
#define pb push_back
#define pf push_front
#define popb pop_back
#define popf pop_front
#define all(x) x.begin(),x.end()
#define ff(i,a,b) for (int i = a; i < b; i++)
#define fff(i,a,b) for (int i = a; i <= b; i++)
#define bff(i,a,b) for (int i = b-1; i >= a; i--)
#define bfff(i,a,b) for (int i = b; i >= a; i--)
using namespace std;
long double typedef ld;
unsigned int typedef ui;
long long int typedef li;
pair<int,int> typedef pii;
pair<li,li> typedef pli;
pair<ld,ld> typedef pld;
vector<vector<int>> typedef graph;
unsigned long long int typedef ull;
//const int mod = 998244353;
const int mod = 1000000007;
//Note to self: Check for overflow
graph g(500005);
vector<int> listovi;
void dfs(int p, int q)
{
if ((int)g[p].size()==1) listovi.pb(p);
for (auto it : g[p]) if (it!=q) dfs(it,p);
}
int main()
{
FAST;
int n; cin>>n;
ff(i,1,n)
{
int u,v; cin>>u>>v;
g[u].pb(v),g[v].pb(u);
}
int root=-1;
fff(i,1,n) if ((int)g[i].size()!=1) root=i;
dfs(root,-1);
vector<pii> ans;
int m=(listovi).size();
ff(i,0,(m+1)/2) ans.pb({listovi[i],listovi[(i+m/2)%m]});
cout<<(int)ans.size()<<"\n";
for (auto it : ans) cout<<it.xx<<" "<<it.yy<<"\n";
}
//Note to self: Check for overflow
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
7 ms |
11988 KB |
Output is correct |
2 |
Correct |
7 ms |
11988 KB |
Output is correct |
3 |
Correct |
6 ms |
12036 KB |
Output is correct |
4 |
Correct |
6 ms |
12052 KB |
Output is correct |
5 |
Correct |
6 ms |
11988 KB |
Output is correct |
6 |
Correct |
7 ms |
11988 KB |
Output is correct |
7 |
Correct |
6 ms |
11988 KB |
Output is correct |
8 |
Correct |
7 ms |
11988 KB |
Output is correct |
9 |
Correct |
6 ms |
11988 KB |
Output is correct |
10 |
Correct |
6 ms |
11988 KB |
Output is correct |
11 |
Correct |
6 ms |
11988 KB |
Output is correct |
12 |
Correct |
6 ms |
11988 KB |
Output is correct |
13 |
Correct |
7 ms |
11948 KB |
Output is correct |
14 |
Correct |
6 ms |
11988 KB |
Output is correct |
15 |
Correct |
6 ms |
12072 KB |
Output is correct |
16 |
Correct |
7 ms |
11988 KB |
Output is correct |
17 |
Correct |
7 ms |
11988 KB |
Output is correct |
18 |
Correct |
6 ms |
11988 KB |
Output is correct |
19 |
Correct |
7 ms |
11988 KB |
Output is correct |
20 |
Correct |
7 ms |
12032 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
7 ms |
11988 KB |
Output is correct |
2 |
Correct |
7 ms |
11988 KB |
Output is correct |
3 |
Correct |
6 ms |
12036 KB |
Output is correct |
4 |
Correct |
6 ms |
12052 KB |
Output is correct |
5 |
Correct |
6 ms |
11988 KB |
Output is correct |
6 |
Correct |
7 ms |
11988 KB |
Output is correct |
7 |
Correct |
6 ms |
11988 KB |
Output is correct |
8 |
Correct |
7 ms |
11988 KB |
Output is correct |
9 |
Correct |
6 ms |
11988 KB |
Output is correct |
10 |
Correct |
6 ms |
11988 KB |
Output is correct |
11 |
Correct |
6 ms |
11988 KB |
Output is correct |
12 |
Correct |
6 ms |
11988 KB |
Output is correct |
13 |
Correct |
7 ms |
11948 KB |
Output is correct |
14 |
Correct |
6 ms |
11988 KB |
Output is correct |
15 |
Correct |
6 ms |
12072 KB |
Output is correct |
16 |
Correct |
7 ms |
11988 KB |
Output is correct |
17 |
Correct |
7 ms |
11988 KB |
Output is correct |
18 |
Correct |
6 ms |
11988 KB |
Output is correct |
19 |
Correct |
7 ms |
11988 KB |
Output is correct |
20 |
Correct |
7 ms |
12032 KB |
Output is correct |
21 |
Correct |
7 ms |
11988 KB |
Output is correct |
22 |
Correct |
7 ms |
12092 KB |
Output is correct |
23 |
Correct |
7 ms |
12096 KB |
Output is correct |
24 |
Correct |
8 ms |
12088 KB |
Output is correct |
25 |
Correct |
9 ms |
12084 KB |
Output is correct |
26 |
Correct |
7 ms |
12116 KB |
Output is correct |
27 |
Correct |
8 ms |
12092 KB |
Output is correct |
28 |
Correct |
7 ms |
12088 KB |
Output is correct |
29 |
Correct |
7 ms |
12116 KB |
Output is correct |
30 |
Correct |
7 ms |
11988 KB |
Output is correct |
31 |
Correct |
7 ms |
12088 KB |
Output is correct |
32 |
Correct |
7 ms |
11988 KB |
Output is correct |
33 |
Correct |
6 ms |
11988 KB |
Output is correct |
34 |
Correct |
6 ms |
11988 KB |
Output is correct |
35 |
Correct |
7 ms |
11988 KB |
Output is correct |
36 |
Correct |
7 ms |
12076 KB |
Output is correct |
37 |
Correct |
7 ms |
11988 KB |
Output is correct |
38 |
Correct |
6 ms |
12088 KB |
Output is correct |
39 |
Correct |
7 ms |
11988 KB |
Output is correct |
40 |
Correct |
7 ms |
11988 KB |
Output is correct |
41 |
Correct |
6 ms |
11988 KB |
Output is correct |
42 |
Correct |
6 ms |
12072 KB |
Output is correct |
43 |
Correct |
7 ms |
12088 KB |
Output is correct |
44 |
Correct |
7 ms |
11988 KB |
Output is correct |
45 |
Correct |
7 ms |
11988 KB |
Output is correct |
46 |
Correct |
7 ms |
12116 KB |
Output is correct |
47 |
Correct |
7 ms |
11988 KB |
Output is correct |
48 |
Correct |
6 ms |
11988 KB |
Output is correct |
49 |
Correct |
7 ms |
12088 KB |
Output is correct |
50 |
Correct |
7 ms |
12008 KB |
Output is correct |
51 |
Correct |
7 ms |
11988 KB |
Output is correct |
52 |
Correct |
6 ms |
11976 KB |
Output is correct |
53 |
Correct |
6 ms |
12116 KB |
Output is correct |
54 |
Correct |
7 ms |
11988 KB |
Output is correct |
55 |
Correct |
7 ms |
12068 KB |
Output is correct |
56 |
Correct |
6 ms |
11988 KB |
Output is correct |
57 |
Correct |
7 ms |
11988 KB |
Output is correct |
58 |
Correct |
7 ms |
12116 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
7 ms |
11988 KB |
Output is correct |
2 |
Correct |
7 ms |
11988 KB |
Output is correct |
3 |
Correct |
6 ms |
12036 KB |
Output is correct |
4 |
Correct |
6 ms |
12052 KB |
Output is correct |
5 |
Correct |
6 ms |
11988 KB |
Output is correct |
6 |
Correct |
7 ms |
11988 KB |
Output is correct |
7 |
Correct |
6 ms |
11988 KB |
Output is correct |
8 |
Correct |
7 ms |
11988 KB |
Output is correct |
9 |
Correct |
6 ms |
11988 KB |
Output is correct |
10 |
Correct |
6 ms |
11988 KB |
Output is correct |
11 |
Correct |
6 ms |
11988 KB |
Output is correct |
12 |
Correct |
6 ms |
11988 KB |
Output is correct |
13 |
Correct |
7 ms |
11948 KB |
Output is correct |
14 |
Correct |
6 ms |
11988 KB |
Output is correct |
15 |
Correct |
6 ms |
12072 KB |
Output is correct |
16 |
Correct |
7 ms |
11988 KB |
Output is correct |
17 |
Correct |
7 ms |
11988 KB |
Output is correct |
18 |
Correct |
6 ms |
11988 KB |
Output is correct |
19 |
Correct |
7 ms |
11988 KB |
Output is correct |
20 |
Correct |
7 ms |
12032 KB |
Output is correct |
21 |
Correct |
7 ms |
11988 KB |
Output is correct |
22 |
Correct |
7 ms |
12092 KB |
Output is correct |
23 |
Correct |
7 ms |
12096 KB |
Output is correct |
24 |
Correct |
8 ms |
12088 KB |
Output is correct |
25 |
Correct |
9 ms |
12084 KB |
Output is correct |
26 |
Correct |
7 ms |
12116 KB |
Output is correct |
27 |
Correct |
8 ms |
12092 KB |
Output is correct |
28 |
Correct |
7 ms |
12088 KB |
Output is correct |
29 |
Correct |
7 ms |
12116 KB |
Output is correct |
30 |
Correct |
7 ms |
11988 KB |
Output is correct |
31 |
Correct |
7 ms |
12088 KB |
Output is correct |
32 |
Correct |
7 ms |
11988 KB |
Output is correct |
33 |
Correct |
6 ms |
11988 KB |
Output is correct |
34 |
Correct |
6 ms |
11988 KB |
Output is correct |
35 |
Correct |
7 ms |
11988 KB |
Output is correct |
36 |
Correct |
7 ms |
12076 KB |
Output is correct |
37 |
Correct |
7 ms |
11988 KB |
Output is correct |
38 |
Correct |
6 ms |
12088 KB |
Output is correct |
39 |
Correct |
7 ms |
11988 KB |
Output is correct |
40 |
Correct |
7 ms |
11988 KB |
Output is correct |
41 |
Correct |
6 ms |
11988 KB |
Output is correct |
42 |
Correct |
6 ms |
12072 KB |
Output is correct |
43 |
Correct |
7 ms |
12088 KB |
Output is correct |
44 |
Correct |
7 ms |
11988 KB |
Output is correct |
45 |
Correct |
7 ms |
11988 KB |
Output is correct |
46 |
Correct |
7 ms |
12116 KB |
Output is correct |
47 |
Correct |
7 ms |
11988 KB |
Output is correct |
48 |
Correct |
6 ms |
11988 KB |
Output is correct |
49 |
Correct |
7 ms |
12088 KB |
Output is correct |
50 |
Correct |
7 ms |
12008 KB |
Output is correct |
51 |
Correct |
7 ms |
11988 KB |
Output is correct |
52 |
Correct |
6 ms |
11976 KB |
Output is correct |
53 |
Correct |
6 ms |
12116 KB |
Output is correct |
54 |
Correct |
7 ms |
11988 KB |
Output is correct |
55 |
Correct |
7 ms |
12068 KB |
Output is correct |
56 |
Correct |
6 ms |
11988 KB |
Output is correct |
57 |
Correct |
7 ms |
11988 KB |
Output is correct |
58 |
Correct |
7 ms |
12116 KB |
Output is correct |
59 |
Correct |
342 ms |
37132 KB |
Output is correct |
60 |
Correct |
361 ms |
40040 KB |
Output is correct |
61 |
Correct |
6 ms |
11988 KB |
Output is correct |
62 |
Correct |
6 ms |
11988 KB |
Output is correct |
63 |
Correct |
265 ms |
34752 KB |
Output is correct |
64 |
Correct |
9 ms |
12372 KB |
Output is correct |
65 |
Correct |
14 ms |
13780 KB |
Output is correct |
66 |
Correct |
117 ms |
25160 KB |
Output is correct |
67 |
Correct |
413 ms |
57664 KB |
Output is correct |
68 |
Correct |
389 ms |
50732 KB |
Output is correct |
69 |
Correct |
11 ms |
13012 KB |
Output is correct |
70 |
Correct |
72 ms |
21824 KB |
Output is correct |
71 |
Correct |
248 ms |
43764 KB |
Output is correct |
72 |
Correct |
263 ms |
42712 KB |
Output is correct |
73 |
Correct |
68 ms |
19280 KB |
Output is correct |
74 |
Correct |
346 ms |
38620 KB |
Output is correct |
75 |
Correct |
24 ms |
15432 KB |
Output is correct |
76 |
Correct |
260 ms |
43516 KB |
Output is correct |
77 |
Correct |
262 ms |
43596 KB |
Output is correct |
78 |
Correct |
25 ms |
15444 KB |
Output is correct |
79 |
Correct |
384 ms |
45080 KB |
Output is correct |
80 |
Correct |
8 ms |
12244 KB |
Output is correct |
81 |
Correct |
96 ms |
21704 KB |
Output is correct |
82 |
Correct |
331 ms |
41020 KB |
Output is correct |
83 |
Correct |
399 ms |
38692 KB |
Output is correct |
84 |
Correct |
349 ms |
38672 KB |
Output is correct |
85 |
Correct |
376 ms |
38648 KB |
Output is correct |
86 |
Correct |
363 ms |
40216 KB |
Output is correct |
87 |
Correct |
362 ms |
40052 KB |
Output is correct |