#include<bits/stdc++.h>
using namespace std;
#define pb push_back
#define F first
#define S second
#define debug(x) cerr<<#x<<" :"<<x<<"\n"
#define all(x) x.begin(),x.end()
//#define pii pair<int,int>
#define FAST ios_base::sync_with_stdio(false), cin.tie(), cout.tie();
//#define int long long
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
const int maxn = 5e5 + 7;
const int mod = 1e9 + 7;
const int INF = 1e9 + 7;
const int mlog = 20;
const int SQ = 400;
int root;
vector<int> adj[maxn];
vector<int> Leaf;
void dfs(int v,int par = -1)
{
if(adj[v].size() == 1) Leaf.pb(v);
for(int u : adj[v]) if(u != par) dfs(u, v);
}
int main()
{
FAST;
int n;
cin >> n;
for(int i = 1; i < n; i++)
{
int u, v;
cin >> u >> v;
adj[u].pb(v); adj[v].pb(u);
}
root = 1;
dfs(root);
int SZ = (Leaf.size() + 1) >> 1;
cout << SZ << "\n";
for(int i = 0; i < SZ; i++)
cout << Leaf[i] << " " << Leaf[(i + SZ) % Leaf.size()] << "\n";
return 0;
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
8 ms |
11980 KB |
Output is correct |
2 |
Correct |
8 ms |
12040 KB |
Output is correct |
3 |
Correct |
8 ms |
12028 KB |
Output is correct |
4 |
Correct |
8 ms |
11984 KB |
Output is correct |
5 |
Correct |
8 ms |
11940 KB |
Output is correct |
6 |
Correct |
8 ms |
11980 KB |
Output is correct |
7 |
Correct |
8 ms |
11980 KB |
Output is correct |
8 |
Correct |
8 ms |
11944 KB |
Output is correct |
9 |
Correct |
9 ms |
11980 KB |
Output is correct |
10 |
Correct |
8 ms |
11980 KB |
Output is correct |
11 |
Correct |
8 ms |
12056 KB |
Output is correct |
12 |
Correct |
8 ms |
12056 KB |
Output is correct |
13 |
Correct |
8 ms |
11980 KB |
Output is correct |
14 |
Correct |
8 ms |
11980 KB |
Output is correct |
15 |
Correct |
8 ms |
11984 KB |
Output is correct |
16 |
Correct |
8 ms |
11980 KB |
Output is correct |
17 |
Correct |
8 ms |
11980 KB |
Output is correct |
18 |
Correct |
8 ms |
11980 KB |
Output is correct |
19 |
Correct |
8 ms |
11980 KB |
Output is correct |
20 |
Correct |
8 ms |
11980 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
8 ms |
11980 KB |
Output is correct |
2 |
Correct |
8 ms |
12040 KB |
Output is correct |
3 |
Correct |
8 ms |
12028 KB |
Output is correct |
4 |
Correct |
8 ms |
11984 KB |
Output is correct |
5 |
Correct |
8 ms |
11940 KB |
Output is correct |
6 |
Correct |
8 ms |
11980 KB |
Output is correct |
7 |
Correct |
8 ms |
11980 KB |
Output is correct |
8 |
Correct |
8 ms |
11944 KB |
Output is correct |
9 |
Correct |
9 ms |
11980 KB |
Output is correct |
10 |
Correct |
8 ms |
11980 KB |
Output is correct |
11 |
Correct |
8 ms |
12056 KB |
Output is correct |
12 |
Correct |
8 ms |
12056 KB |
Output is correct |
13 |
Correct |
8 ms |
11980 KB |
Output is correct |
14 |
Correct |
8 ms |
11980 KB |
Output is correct |
15 |
Correct |
8 ms |
11984 KB |
Output is correct |
16 |
Correct |
8 ms |
11980 KB |
Output is correct |
17 |
Correct |
8 ms |
11980 KB |
Output is correct |
18 |
Correct |
8 ms |
11980 KB |
Output is correct |
19 |
Correct |
8 ms |
11980 KB |
Output is correct |
20 |
Correct |
8 ms |
11980 KB |
Output is correct |
21 |
Correct |
8 ms |
11980 KB |
Output is correct |
22 |
Correct |
9 ms |
12108 KB |
Output is correct |
23 |
Correct |
9 ms |
12108 KB |
Output is correct |
24 |
Correct |
9 ms |
12108 KB |
Output is correct |
25 |
Correct |
9 ms |
12108 KB |
Output is correct |
26 |
Correct |
9 ms |
12112 KB |
Output is correct |
27 |
Correct |
9 ms |
12108 KB |
Output is correct |
28 |
Correct |
9 ms |
12108 KB |
Output is correct |
29 |
Correct |
9 ms |
12108 KB |
Output is correct |
30 |
Correct |
8 ms |
11980 KB |
Output is correct |
31 |
Correct |
10 ms |
12108 KB |
Output is correct |
32 |
Correct |
8 ms |
11980 KB |
Output is correct |
33 |
Correct |
8 ms |
12012 KB |
Output is correct |
34 |
Correct |
8 ms |
11980 KB |
Output is correct |
35 |
Correct |
8 ms |
11980 KB |
Output is correct |
36 |
Correct |
9 ms |
11980 KB |
Output is correct |
37 |
Correct |
8 ms |
12096 KB |
Output is correct |
38 |
Correct |
9 ms |
12108 KB |
Output is correct |
39 |
Correct |
8 ms |
12004 KB |
Output is correct |
40 |
Correct |
8 ms |
11980 KB |
Output is correct |
41 |
Correct |
8 ms |
11980 KB |
Output is correct |
42 |
Correct |
8 ms |
11980 KB |
Output is correct |
43 |
Correct |
8 ms |
12108 KB |
Output is correct |
44 |
Correct |
8 ms |
11980 KB |
Output is correct |
45 |
Correct |
8 ms |
11980 KB |
Output is correct |
46 |
Correct |
8 ms |
12076 KB |
Output is correct |
47 |
Correct |
8 ms |
11980 KB |
Output is correct |
48 |
Correct |
8 ms |
11980 KB |
Output is correct |
49 |
Correct |
8 ms |
12060 KB |
Output is correct |
50 |
Correct |
8 ms |
11980 KB |
Output is correct |
51 |
Correct |
8 ms |
11980 KB |
Output is correct |
52 |
Correct |
8 ms |
12080 KB |
Output is correct |
53 |
Correct |
8 ms |
12108 KB |
Output is correct |
54 |
Correct |
9 ms |
11984 KB |
Output is correct |
55 |
Correct |
8 ms |
11992 KB |
Output is correct |
56 |
Correct |
8 ms |
11980 KB |
Output is correct |
57 |
Correct |
9 ms |
12068 KB |
Output is correct |
58 |
Correct |
9 ms |
12164 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
8 ms |
11980 KB |
Output is correct |
2 |
Correct |
8 ms |
12040 KB |
Output is correct |
3 |
Correct |
8 ms |
12028 KB |
Output is correct |
4 |
Correct |
8 ms |
11984 KB |
Output is correct |
5 |
Correct |
8 ms |
11940 KB |
Output is correct |
6 |
Correct |
8 ms |
11980 KB |
Output is correct |
7 |
Correct |
8 ms |
11980 KB |
Output is correct |
8 |
Correct |
8 ms |
11944 KB |
Output is correct |
9 |
Correct |
9 ms |
11980 KB |
Output is correct |
10 |
Correct |
8 ms |
11980 KB |
Output is correct |
11 |
Correct |
8 ms |
12056 KB |
Output is correct |
12 |
Correct |
8 ms |
12056 KB |
Output is correct |
13 |
Correct |
8 ms |
11980 KB |
Output is correct |
14 |
Correct |
8 ms |
11980 KB |
Output is correct |
15 |
Correct |
8 ms |
11984 KB |
Output is correct |
16 |
Correct |
8 ms |
11980 KB |
Output is correct |
17 |
Correct |
8 ms |
11980 KB |
Output is correct |
18 |
Correct |
8 ms |
11980 KB |
Output is correct |
19 |
Correct |
8 ms |
11980 KB |
Output is correct |
20 |
Correct |
8 ms |
11980 KB |
Output is correct |
21 |
Correct |
8 ms |
11980 KB |
Output is correct |
22 |
Correct |
9 ms |
12108 KB |
Output is correct |
23 |
Correct |
9 ms |
12108 KB |
Output is correct |
24 |
Correct |
9 ms |
12108 KB |
Output is correct |
25 |
Correct |
9 ms |
12108 KB |
Output is correct |
26 |
Correct |
9 ms |
12112 KB |
Output is correct |
27 |
Correct |
9 ms |
12108 KB |
Output is correct |
28 |
Correct |
9 ms |
12108 KB |
Output is correct |
29 |
Correct |
9 ms |
12108 KB |
Output is correct |
30 |
Correct |
8 ms |
11980 KB |
Output is correct |
31 |
Correct |
10 ms |
12108 KB |
Output is correct |
32 |
Correct |
8 ms |
11980 KB |
Output is correct |
33 |
Correct |
8 ms |
12012 KB |
Output is correct |
34 |
Correct |
8 ms |
11980 KB |
Output is correct |
35 |
Correct |
8 ms |
11980 KB |
Output is correct |
36 |
Correct |
9 ms |
11980 KB |
Output is correct |
37 |
Correct |
8 ms |
12096 KB |
Output is correct |
38 |
Correct |
9 ms |
12108 KB |
Output is correct |
39 |
Correct |
8 ms |
12004 KB |
Output is correct |
40 |
Correct |
8 ms |
11980 KB |
Output is correct |
41 |
Correct |
8 ms |
11980 KB |
Output is correct |
42 |
Correct |
8 ms |
11980 KB |
Output is correct |
43 |
Correct |
8 ms |
12108 KB |
Output is correct |
44 |
Correct |
8 ms |
11980 KB |
Output is correct |
45 |
Correct |
8 ms |
11980 KB |
Output is correct |
46 |
Correct |
8 ms |
12076 KB |
Output is correct |
47 |
Correct |
8 ms |
11980 KB |
Output is correct |
48 |
Correct |
8 ms |
11980 KB |
Output is correct |
49 |
Correct |
8 ms |
12060 KB |
Output is correct |
50 |
Correct |
8 ms |
11980 KB |
Output is correct |
51 |
Correct |
8 ms |
11980 KB |
Output is correct |
52 |
Correct |
8 ms |
12080 KB |
Output is correct |
53 |
Correct |
8 ms |
12108 KB |
Output is correct |
54 |
Correct |
9 ms |
11984 KB |
Output is correct |
55 |
Correct |
8 ms |
11992 KB |
Output is correct |
56 |
Correct |
8 ms |
11980 KB |
Output is correct |
57 |
Correct |
9 ms |
12068 KB |
Output is correct |
58 |
Correct |
9 ms |
12164 KB |
Output is correct |
59 |
Correct |
370 ms |
29996 KB |
Output is correct |
60 |
Correct |
448 ms |
32056 KB |
Output is correct |
61 |
Correct |
8 ms |
11980 KB |
Output is correct |
62 |
Correct |
9 ms |
12056 KB |
Output is correct |
63 |
Correct |
325 ms |
28272 KB |
Output is correct |
64 |
Correct |
10 ms |
12492 KB |
Output is correct |
65 |
Correct |
19 ms |
13952 KB |
Output is correct |
66 |
Correct |
141 ms |
28248 KB |
Output is correct |
67 |
Correct |
480 ms |
44484 KB |
Output is correct |
68 |
Correct |
478 ms |
45248 KB |
Output is correct |
69 |
Correct |
15 ms |
12748 KB |
Output is correct |
70 |
Correct |
89 ms |
19156 KB |
Output is correct |
71 |
Correct |
311 ms |
35212 KB |
Output is correct |
72 |
Correct |
333 ms |
34352 KB |
Output is correct |
73 |
Correct |
90 ms |
17480 KB |
Output is correct |
74 |
Correct |
452 ms |
31028 KB |
Output is correct |
75 |
Correct |
32 ms |
14652 KB |
Output is correct |
76 |
Correct |
329 ms |
34864 KB |
Output is correct |
77 |
Correct |
328 ms |
35104 KB |
Output is correct |
78 |
Correct |
34 ms |
14996 KB |
Output is correct |
79 |
Correct |
485 ms |
42148 KB |
Output is correct |
80 |
Correct |
9 ms |
12236 KB |
Output is correct |
81 |
Correct |
107 ms |
19228 KB |
Output is correct |
82 |
Correct |
390 ms |
33128 KB |
Output is correct |
83 |
Correct |
448 ms |
31024 KB |
Output is correct |
84 |
Correct |
466 ms |
30964 KB |
Output is correct |
85 |
Correct |
436 ms |
31028 KB |
Output is correct |
86 |
Correct |
454 ms |
32044 KB |
Output is correct |
87 |
Correct |
435 ms |
32132 KB |
Output is correct |