#include <bits/stdc++.h>
using namespace std;
const int mxN = 5e5 + 12;
vector<int> adj[mxN];
vector<int> lisce;
void dfs(int s, int p = -1) {
if(adj[s].size() == 1) lisce.push_back(s);
for(auto e : adj[s]) {
if(e == p) continue;
dfs(e, s);
}
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
int n;
cin >> n;
for(int i = 1; i < n; ++i) {
int u, v;
cin >> u >> v;
--u, --v;
adj[u].push_back(v);
adj[v].push_back(u);
}
dfs(0);
int vel = lisce.size();
cout << (vel + 1) / 2 << '\n';
for(int i = 0; i < (vel + 1) / 2; ++i) {
int x = lisce[i];
int y = lisce[(i + vel / 2) % vel];
cout << x + 1 << " " << y + 1 << '\n';
}
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
6 ms |
11988 KB |
Output is correct |
2 |
Correct |
7 ms |
12072 KB |
Output is correct |
3 |
Correct |
7 ms |
12064 KB |
Output is correct |
4 |
Correct |
8 ms |
12064 KB |
Output is correct |
5 |
Correct |
7 ms |
11988 KB |
Output is correct |
6 |
Correct |
6 ms |
11988 KB |
Output is correct |
7 |
Correct |
7 ms |
12064 KB |
Output is correct |
8 |
Correct |
6 ms |
11988 KB |
Output is correct |
9 |
Correct |
6 ms |
12060 KB |
Output is correct |
10 |
Correct |
7 ms |
12068 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 |
11988 KB |
Output is correct |
14 |
Correct |
6 ms |
11988 KB |
Output is correct |
15 |
Correct |
6 ms |
12060 KB |
Output is correct |
16 |
Correct |
8 ms |
11988 KB |
Output is correct |
17 |
Correct |
6 ms |
11988 KB |
Output is correct |
18 |
Correct |
6 ms |
11988 KB |
Output is correct |
19 |
Correct |
6 ms |
11988 KB |
Output is correct |
20 |
Correct |
7 ms |
11988 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
6 ms |
11988 KB |
Output is correct |
2 |
Correct |
7 ms |
12072 KB |
Output is correct |
3 |
Correct |
7 ms |
12064 KB |
Output is correct |
4 |
Correct |
8 ms |
12064 KB |
Output is correct |
5 |
Correct |
7 ms |
11988 KB |
Output is correct |
6 |
Correct |
6 ms |
11988 KB |
Output is correct |
7 |
Correct |
7 ms |
12064 KB |
Output is correct |
8 |
Correct |
6 ms |
11988 KB |
Output is correct |
9 |
Correct |
6 ms |
12060 KB |
Output is correct |
10 |
Correct |
7 ms |
12068 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 |
11988 KB |
Output is correct |
14 |
Correct |
6 ms |
11988 KB |
Output is correct |
15 |
Correct |
6 ms |
12060 KB |
Output is correct |
16 |
Correct |
8 ms |
11988 KB |
Output is correct |
17 |
Correct |
6 ms |
11988 KB |
Output is correct |
18 |
Correct |
6 ms |
11988 KB |
Output is correct |
19 |
Correct |
6 ms |
11988 KB |
Output is correct |
20 |
Correct |
7 ms |
11988 KB |
Output is correct |
21 |
Correct |
6 ms |
12064 KB |
Output is correct |
22 |
Correct |
7 ms |
12180 KB |
Output is correct |
23 |
Correct |
7 ms |
12120 KB |
Output is correct |
24 |
Correct |
7 ms |
12116 KB |
Output is correct |
25 |
Correct |
7 ms |
12116 KB |
Output is correct |
26 |
Correct |
7 ms |
12092 KB |
Output is correct |
27 |
Correct |
9 ms |
12116 KB |
Output is correct |
28 |
Correct |
8 ms |
12116 KB |
Output is correct |
29 |
Correct |
8 ms |
12068 KB |
Output is correct |
30 |
Correct |
8 ms |
11988 KB |
Output is correct |
31 |
Correct |
8 ms |
12116 KB |
Output is correct |
32 |
Correct |
7 ms |
11988 KB |
Output is correct |
33 |
Correct |
6 ms |
11988 KB |
Output is correct |
34 |
Correct |
7 ms |
11996 KB |
Output is correct |
35 |
Correct |
7 ms |
12068 KB |
Output is correct |
36 |
Correct |
7 ms |
12032 KB |
Output is correct |
37 |
Correct |
9 ms |
11988 KB |
Output is correct |
38 |
Correct |
6 ms |
12116 KB |
Output is correct |
39 |
Correct |
9 ms |
12040 KB |
Output is correct |
40 |
Correct |
7 ms |
12064 KB |
Output is correct |
41 |
Correct |
6 ms |
11988 KB |
Output is correct |
42 |
Correct |
6 ms |
12064 KB |
Output is correct |
43 |
Correct |
7 ms |
12116 KB |
Output is correct |
44 |
Correct |
6 ms |
11988 KB |
Output is correct |
45 |
Correct |
9 ms |
11988 KB |
Output is correct |
46 |
Correct |
7 ms |
12052 KB |
Output is correct |
47 |
Correct |
6 ms |
12068 KB |
Output is correct |
48 |
Correct |
6 ms |
12060 KB |
Output is correct |
49 |
Correct |
7 ms |
12116 KB |
Output is correct |
50 |
Correct |
6 ms |
11988 KB |
Output is correct |
51 |
Correct |
7 ms |
11988 KB |
Output is correct |
52 |
Correct |
6 ms |
11988 KB |
Output is correct |
53 |
Correct |
7 ms |
12116 KB |
Output is correct |
54 |
Correct |
9 ms |
11988 KB |
Output is correct |
55 |
Correct |
7 ms |
11988 KB |
Output is correct |
56 |
Correct |
7 ms |
11988 KB |
Output is correct |
57 |
Correct |
6 ms |
11988 KB |
Output is correct |
58 |
Correct |
7 ms |
12116 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
6 ms |
11988 KB |
Output is correct |
2 |
Correct |
7 ms |
12072 KB |
Output is correct |
3 |
Correct |
7 ms |
12064 KB |
Output is correct |
4 |
Correct |
8 ms |
12064 KB |
Output is correct |
5 |
Correct |
7 ms |
11988 KB |
Output is correct |
6 |
Correct |
6 ms |
11988 KB |
Output is correct |
7 |
Correct |
7 ms |
12064 KB |
Output is correct |
8 |
Correct |
6 ms |
11988 KB |
Output is correct |
9 |
Correct |
6 ms |
12060 KB |
Output is correct |
10 |
Correct |
7 ms |
12068 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 |
11988 KB |
Output is correct |
14 |
Correct |
6 ms |
11988 KB |
Output is correct |
15 |
Correct |
6 ms |
12060 KB |
Output is correct |
16 |
Correct |
8 ms |
11988 KB |
Output is correct |
17 |
Correct |
6 ms |
11988 KB |
Output is correct |
18 |
Correct |
6 ms |
11988 KB |
Output is correct |
19 |
Correct |
6 ms |
11988 KB |
Output is correct |
20 |
Correct |
7 ms |
11988 KB |
Output is correct |
21 |
Correct |
6 ms |
12064 KB |
Output is correct |
22 |
Correct |
7 ms |
12180 KB |
Output is correct |
23 |
Correct |
7 ms |
12120 KB |
Output is correct |
24 |
Correct |
7 ms |
12116 KB |
Output is correct |
25 |
Correct |
7 ms |
12116 KB |
Output is correct |
26 |
Correct |
7 ms |
12092 KB |
Output is correct |
27 |
Correct |
9 ms |
12116 KB |
Output is correct |
28 |
Correct |
8 ms |
12116 KB |
Output is correct |
29 |
Correct |
8 ms |
12068 KB |
Output is correct |
30 |
Correct |
8 ms |
11988 KB |
Output is correct |
31 |
Correct |
8 ms |
12116 KB |
Output is correct |
32 |
Correct |
7 ms |
11988 KB |
Output is correct |
33 |
Correct |
6 ms |
11988 KB |
Output is correct |
34 |
Correct |
7 ms |
11996 KB |
Output is correct |
35 |
Correct |
7 ms |
12068 KB |
Output is correct |
36 |
Correct |
7 ms |
12032 KB |
Output is correct |
37 |
Correct |
9 ms |
11988 KB |
Output is correct |
38 |
Correct |
6 ms |
12116 KB |
Output is correct |
39 |
Correct |
9 ms |
12040 KB |
Output is correct |
40 |
Correct |
7 ms |
12064 KB |
Output is correct |
41 |
Correct |
6 ms |
11988 KB |
Output is correct |
42 |
Correct |
6 ms |
12064 KB |
Output is correct |
43 |
Correct |
7 ms |
12116 KB |
Output is correct |
44 |
Correct |
6 ms |
11988 KB |
Output is correct |
45 |
Correct |
9 ms |
11988 KB |
Output is correct |
46 |
Correct |
7 ms |
12052 KB |
Output is correct |
47 |
Correct |
6 ms |
12068 KB |
Output is correct |
48 |
Correct |
6 ms |
12060 KB |
Output is correct |
49 |
Correct |
7 ms |
12116 KB |
Output is correct |
50 |
Correct |
6 ms |
11988 KB |
Output is correct |
51 |
Correct |
7 ms |
11988 KB |
Output is correct |
52 |
Correct |
6 ms |
11988 KB |
Output is correct |
53 |
Correct |
7 ms |
12116 KB |
Output is correct |
54 |
Correct |
9 ms |
11988 KB |
Output is correct |
55 |
Correct |
7 ms |
11988 KB |
Output is correct |
56 |
Correct |
7 ms |
11988 KB |
Output is correct |
57 |
Correct |
6 ms |
11988 KB |
Output is correct |
58 |
Correct |
7 ms |
12116 KB |
Output is correct |
59 |
Correct |
316 ms |
36040 KB |
Output is correct |
60 |
Correct |
378 ms |
38652 KB |
Output is correct |
61 |
Correct |
9 ms |
11988 KB |
Output is correct |
62 |
Correct |
6 ms |
11964 KB |
Output is correct |
63 |
Correct |
289 ms |
33496 KB |
Output is correct |
64 |
Correct |
8 ms |
12372 KB |
Output is correct |
65 |
Correct |
20 ms |
13828 KB |
Output is correct |
66 |
Correct |
112 ms |
27804 KB |
Output is correct |
67 |
Correct |
452 ms |
46900 KB |
Output is correct |
68 |
Correct |
495 ms |
47664 KB |
Output is correct |
69 |
Correct |
12 ms |
12884 KB |
Output is correct |
70 |
Correct |
85 ms |
21224 KB |
Output is correct |
71 |
Correct |
246 ms |
41784 KB |
Output is correct |
72 |
Correct |
267 ms |
40676 KB |
Output is correct |
73 |
Correct |
88 ms |
19064 KB |
Output is correct |
74 |
Correct |
359 ms |
37584 KB |
Output is correct |
75 |
Correct |
25 ms |
15244 KB |
Output is correct |
76 |
Correct |
265 ms |
41496 KB |
Output is correct |
77 |
Correct |
238 ms |
41620 KB |
Output is correct |
78 |
Correct |
30 ms |
15308 KB |
Output is correct |
79 |
Correct |
397 ms |
45144 KB |
Output is correct |
80 |
Correct |
9 ms |
12244 KB |
Output is correct |
81 |
Correct |
82 ms |
21300 KB |
Output is correct |
82 |
Correct |
303 ms |
39564 KB |
Output is correct |
83 |
Correct |
392 ms |
37688 KB |
Output is correct |
84 |
Correct |
342 ms |
37692 KB |
Output is correct |
85 |
Correct |
359 ms |
37716 KB |
Output is correct |
86 |
Correct |
358 ms |
38720 KB |
Output is correct |
87 |
Correct |
352 ms |
38736 KB |
Output is correct |