/* * In the name of GOD */
#include "bits/stdc++.h"
using namespace std;
typedef long long ll;
typedef pair <int, int> pii;
#define F first
#define S second
#define mk make_pair
const int N = 501234;
int st[N], ts[N], cnt = 0;
vector <int> g[N], k;
void dfs(int v, int p) {
st[v] = cnt;
ts[cnt] = v;
cnt++;
if (g[v].size() == 1)
k.push_back(st[v]);
for (auto u : g[v]) {
if (u != p) {
dfs(u, v);
}
}
}
int32_t main() {
ios::sync_with_stdio(false);
cin.tie();
cout.tie();
int n;
cin >> n;
int root;
for (int i = 0; i < n - 1; i++) {
int u, v;
cin >> u >> v;
g[u].push_back(v);
g[v].push_back(u);
if (g[u].size() >= 2)
root = u;
if (g[v].size() >= 2)
root = v;
}
dfs(root, -1);
cout << ((int)k.size() + 1) / 2 << '\n';
sort(k.begin(), k.end());
for (int i = 0; i < ((int)k.size() + 1) / 2; i++)
cout << ts[k[i]] << ' ' << ts[k[i + ((int)k.size()) / 2]] << '\n';
}
Compilation message
net.cpp: In function 'int32_t main()':
net.cpp:46:5: warning: 'root' may be used uninitialized in this function [-Wmaybe-uninitialized]
46 | dfs(root, -1);
| ~~~^~~~~~~~~~
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
7 ms |
11988 KB |
Output is correct |
2 |
Correct |
6 ms |
12100 KB |
Output is correct |
3 |
Correct |
6 ms |
12096 KB |
Output is correct |
4 |
Correct |
6 ms |
12104 KB |
Output is correct |
5 |
Correct |
7 ms |
11988 KB |
Output is correct |
6 |
Correct |
8 ms |
12048 KB |
Output is correct |
7 |
Correct |
7 ms |
12048 KB |
Output is correct |
8 |
Correct |
8 ms |
12116 KB |
Output is correct |
9 |
Correct |
7 ms |
11996 KB |
Output is correct |
10 |
Correct |
6 ms |
12100 KB |
Output is correct |
11 |
Correct |
6 ms |
12044 KB |
Output is correct |
12 |
Correct |
6 ms |
12100 KB |
Output is correct |
13 |
Correct |
6 ms |
12100 KB |
Output is correct |
14 |
Correct |
6 ms |
11988 KB |
Output is correct |
15 |
Correct |
6 ms |
11988 KB |
Output is correct |
16 |
Correct |
6 ms |
12100 KB |
Output is correct |
17 |
Correct |
7 ms |
11988 KB |
Output is correct |
18 |
Correct |
7 ms |
11988 KB |
Output is correct |
19 |
Correct |
6 ms |
11988 KB |
Output is correct |
20 |
Correct |
7 ms |
12136 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
7 ms |
11988 KB |
Output is correct |
2 |
Correct |
6 ms |
12100 KB |
Output is correct |
3 |
Correct |
6 ms |
12096 KB |
Output is correct |
4 |
Correct |
6 ms |
12104 KB |
Output is correct |
5 |
Correct |
7 ms |
11988 KB |
Output is correct |
6 |
Correct |
8 ms |
12048 KB |
Output is correct |
7 |
Correct |
7 ms |
12048 KB |
Output is correct |
8 |
Correct |
8 ms |
12116 KB |
Output is correct |
9 |
Correct |
7 ms |
11996 KB |
Output is correct |
10 |
Correct |
6 ms |
12100 KB |
Output is correct |
11 |
Correct |
6 ms |
12044 KB |
Output is correct |
12 |
Correct |
6 ms |
12100 KB |
Output is correct |
13 |
Correct |
6 ms |
12100 KB |
Output is correct |
14 |
Correct |
6 ms |
11988 KB |
Output is correct |
15 |
Correct |
6 ms |
11988 KB |
Output is correct |
16 |
Correct |
6 ms |
12100 KB |
Output is correct |
17 |
Correct |
7 ms |
11988 KB |
Output is correct |
18 |
Correct |
7 ms |
11988 KB |
Output is correct |
19 |
Correct |
6 ms |
11988 KB |
Output is correct |
20 |
Correct |
7 ms |
12136 KB |
Output is correct |
21 |
Correct |
6 ms |
11988 KB |
Output is correct |
22 |
Correct |
7 ms |
12244 KB |
Output is correct |
23 |
Correct |
8 ms |
12244 KB |
Output is correct |
24 |
Correct |
7 ms |
12244 KB |
Output is correct |
25 |
Correct |
7 ms |
12128 KB |
Output is correct |
26 |
Correct |
7 ms |
12116 KB |
Output is correct |
27 |
Correct |
7 ms |
12116 KB |
Output is correct |
28 |
Correct |
8 ms |
12112 KB |
Output is correct |
29 |
Correct |
7 ms |
12116 KB |
Output is correct |
30 |
Correct |
8 ms |
12100 KB |
Output is correct |
31 |
Correct |
7 ms |
12208 KB |
Output is correct |
32 |
Correct |
6 ms |
12100 KB |
Output is correct |
33 |
Correct |
6 ms |
12020 KB |
Output is correct |
34 |
Correct |
6 ms |
12116 KB |
Output is correct |
35 |
Correct |
6 ms |
11988 KB |
Output is correct |
36 |
Correct |
7 ms |
12116 KB |
Output is correct |
37 |
Correct |
6 ms |
12104 KB |
Output is correct |
38 |
Correct |
7 ms |
12100 KB |
Output is correct |
39 |
Correct |
6 ms |
12080 KB |
Output is correct |
40 |
Correct |
7 ms |
12164 KB |
Output is correct |
41 |
Correct |
7 ms |
11988 KB |
Output is correct |
42 |
Correct |
6 ms |
12100 KB |
Output is correct |
43 |
Correct |
7 ms |
12104 KB |
Output is correct |
44 |
Correct |
7 ms |
11988 KB |
Output is correct |
45 |
Correct |
7 ms |
12116 KB |
Output is correct |
46 |
Correct |
7 ms |
12116 KB |
Output is correct |
47 |
Correct |
7 ms |
11988 KB |
Output is correct |
48 |
Correct |
9 ms |
12036 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 |
12116 KB |
Output is correct |
53 |
Correct |
7 ms |
12116 KB |
Output is correct |
54 |
Correct |
6 ms |
11988 KB |
Output is correct |
55 |
Correct |
6 ms |
12116 KB |
Output is correct |
56 |
Correct |
7 ms |
12032 KB |
Output is correct |
57 |
Correct |
7 ms |
12116 KB |
Output is correct |
58 |
Correct |
8 ms |
12236 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
7 ms |
11988 KB |
Output is correct |
2 |
Correct |
6 ms |
12100 KB |
Output is correct |
3 |
Correct |
6 ms |
12096 KB |
Output is correct |
4 |
Correct |
6 ms |
12104 KB |
Output is correct |
5 |
Correct |
7 ms |
11988 KB |
Output is correct |
6 |
Correct |
8 ms |
12048 KB |
Output is correct |
7 |
Correct |
7 ms |
12048 KB |
Output is correct |
8 |
Correct |
8 ms |
12116 KB |
Output is correct |
9 |
Correct |
7 ms |
11996 KB |
Output is correct |
10 |
Correct |
6 ms |
12100 KB |
Output is correct |
11 |
Correct |
6 ms |
12044 KB |
Output is correct |
12 |
Correct |
6 ms |
12100 KB |
Output is correct |
13 |
Correct |
6 ms |
12100 KB |
Output is correct |
14 |
Correct |
6 ms |
11988 KB |
Output is correct |
15 |
Correct |
6 ms |
11988 KB |
Output is correct |
16 |
Correct |
6 ms |
12100 KB |
Output is correct |
17 |
Correct |
7 ms |
11988 KB |
Output is correct |
18 |
Correct |
7 ms |
11988 KB |
Output is correct |
19 |
Correct |
6 ms |
11988 KB |
Output is correct |
20 |
Correct |
7 ms |
12136 KB |
Output is correct |
21 |
Correct |
6 ms |
11988 KB |
Output is correct |
22 |
Correct |
7 ms |
12244 KB |
Output is correct |
23 |
Correct |
8 ms |
12244 KB |
Output is correct |
24 |
Correct |
7 ms |
12244 KB |
Output is correct |
25 |
Correct |
7 ms |
12128 KB |
Output is correct |
26 |
Correct |
7 ms |
12116 KB |
Output is correct |
27 |
Correct |
7 ms |
12116 KB |
Output is correct |
28 |
Correct |
8 ms |
12112 KB |
Output is correct |
29 |
Correct |
7 ms |
12116 KB |
Output is correct |
30 |
Correct |
8 ms |
12100 KB |
Output is correct |
31 |
Correct |
7 ms |
12208 KB |
Output is correct |
32 |
Correct |
6 ms |
12100 KB |
Output is correct |
33 |
Correct |
6 ms |
12020 KB |
Output is correct |
34 |
Correct |
6 ms |
12116 KB |
Output is correct |
35 |
Correct |
6 ms |
11988 KB |
Output is correct |
36 |
Correct |
7 ms |
12116 KB |
Output is correct |
37 |
Correct |
6 ms |
12104 KB |
Output is correct |
38 |
Correct |
7 ms |
12100 KB |
Output is correct |
39 |
Correct |
6 ms |
12080 KB |
Output is correct |
40 |
Correct |
7 ms |
12164 KB |
Output is correct |
41 |
Correct |
7 ms |
11988 KB |
Output is correct |
42 |
Correct |
6 ms |
12100 KB |
Output is correct |
43 |
Correct |
7 ms |
12104 KB |
Output is correct |
44 |
Correct |
7 ms |
11988 KB |
Output is correct |
45 |
Correct |
7 ms |
12116 KB |
Output is correct |
46 |
Correct |
7 ms |
12116 KB |
Output is correct |
47 |
Correct |
7 ms |
11988 KB |
Output is correct |
48 |
Correct |
9 ms |
12036 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 |
12116 KB |
Output is correct |
53 |
Correct |
7 ms |
12116 KB |
Output is correct |
54 |
Correct |
6 ms |
11988 KB |
Output is correct |
55 |
Correct |
6 ms |
12116 KB |
Output is correct |
56 |
Correct |
7 ms |
12032 KB |
Output is correct |
57 |
Correct |
7 ms |
12116 KB |
Output is correct |
58 |
Correct |
8 ms |
12236 KB |
Output is correct |
59 |
Correct |
294 ms |
39100 KB |
Output is correct |
60 |
Correct |
361 ms |
42108 KB |
Output is correct |
61 |
Correct |
7 ms |
11988 KB |
Output is correct |
62 |
Correct |
7 ms |
12100 KB |
Output is correct |
63 |
Correct |
272 ms |
36464 KB |
Output is correct |
64 |
Correct |
8 ms |
12448 KB |
Output is correct |
65 |
Correct |
15 ms |
13996 KB |
Output is correct |
66 |
Correct |
107 ms |
26912 KB |
Output is correct |
67 |
Correct |
405 ms |
60976 KB |
Output is correct |
68 |
Correct |
425 ms |
50812 KB |
Output is correct |
69 |
Correct |
12 ms |
13012 KB |
Output is correct |
70 |
Correct |
73 ms |
22480 KB |
Output is correct |
71 |
Correct |
257 ms |
45304 KB |
Output is correct |
72 |
Correct |
271 ms |
44160 KB |
Output is correct |
73 |
Correct |
76 ms |
20160 KB |
Output is correct |
74 |
Correct |
377 ms |
41048 KB |
Output is correct |
75 |
Correct |
26 ms |
15700 KB |
Output is correct |
76 |
Correct |
264 ms |
45028 KB |
Output is correct |
77 |
Correct |
286 ms |
45000 KB |
Output is correct |
78 |
Correct |
27 ms |
15820 KB |
Output is correct |
79 |
Correct |
394 ms |
52308 KB |
Output is correct |
80 |
Correct |
8 ms |
12244 KB |
Output is correct |
81 |
Correct |
86 ms |
22644 KB |
Output is correct |
82 |
Correct |
320 ms |
42924 KB |
Output is correct |
83 |
Correct |
371 ms |
41092 KB |
Output is correct |
84 |
Correct |
386 ms |
41060 KB |
Output is correct |
85 |
Correct |
364 ms |
41204 KB |
Output is correct |
86 |
Correct |
397 ms |
42168 KB |
Output is correct |
87 |
Correct |
351 ms |
42168 KB |
Output is correct |