#include <bits/stdc++.h>
using namespace std;
int n;
vector <int> g[500001];
vector <int> v; // leaves
bitset <500001> f;
void dfs(int nod)
{
f[nod] = true;
if (g[nod].size() == 1)
v.push_back(nod);
for (auto& i : g[nod])
if (!f[i])
dfs(i);
}
int main() {
cin >> n;
for (int i = 1; i < n; i++)
{
int x, y;
cin >> x >> y;
g[x].push_back(y);
g[y].push_back(x);
}
int root;
for (int i = 1; i <= n; i++)
if (g[i].size() == 1)
{
root = i;
break;
}
dfs(root);
cout << (v.size() + 1) / 2 << '\n';
int i, j;
if (v.size() % 2)
{
i = 0, j = v.size() / 2;
while (i < v.size() / 2)
{
cout << v[i] << ' ' << v[j] << '\n';
i++, j++;
}
cout << v.back() << ' ' << v[0];
}
else
{
i = 0, j = v.size() / 2;
while (i < v.size() / 2)
{
cout << v[i] << ' ' << v[j] << '\n';
i++, j++;
}
}
return 0;
}
Compilation message
net.cpp: In function 'int main()':
net.cpp:51:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
51 | while (i < v.size() / 2)
| ~~^~~~~~~~~~~~~~
net.cpp:63:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
63 | while (i < v.size() / 2)
| ~~^~~~~~~~~~~~~~
net.cpp:41:8: warning: 'root' may be used uninitialized in this function [-Wmaybe-uninitialized]
41 | dfs(root);
| ~~~^~~~~~
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
7 ms |
12032 KB |
Output is correct |
2 |
Correct |
6 ms |
11988 KB |
Output is correct |
3 |
Correct |
6 ms |
11932 KB |
Output is correct |
4 |
Correct |
6 ms |
12040 KB |
Output is correct |
5 |
Correct |
6 ms |
11988 KB |
Output is correct |
6 |
Correct |
6 ms |
12052 KB |
Output is correct |
7 |
Correct |
6 ms |
11988 KB |
Output is correct |
8 |
Correct |
6 ms |
12044 KB |
Output is correct |
9 |
Correct |
6 ms |
11988 KB |
Output is correct |
10 |
Correct |
6 ms |
11992 KB |
Output is correct |
11 |
Correct |
6 ms |
11988 KB |
Output is correct |
12 |
Correct |
6 ms |
12048 KB |
Output is correct |
13 |
Correct |
6 ms |
11988 KB |
Output is correct |
14 |
Correct |
6 ms |
11988 KB |
Output is correct |
15 |
Correct |
7 ms |
11988 KB |
Output is correct |
16 |
Correct |
6 ms |
11988 KB |
Output is correct |
17 |
Correct |
6 ms |
11944 KB |
Output is correct |
18 |
Correct |
6 ms |
11988 KB |
Output is correct |
19 |
Correct |
6 ms |
11988 KB |
Output is correct |
20 |
Correct |
6 ms |
11988 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
7 ms |
12032 KB |
Output is correct |
2 |
Correct |
6 ms |
11988 KB |
Output is correct |
3 |
Correct |
6 ms |
11932 KB |
Output is correct |
4 |
Correct |
6 ms |
12040 KB |
Output is correct |
5 |
Correct |
6 ms |
11988 KB |
Output is correct |
6 |
Correct |
6 ms |
12052 KB |
Output is correct |
7 |
Correct |
6 ms |
11988 KB |
Output is correct |
8 |
Correct |
6 ms |
12044 KB |
Output is correct |
9 |
Correct |
6 ms |
11988 KB |
Output is correct |
10 |
Correct |
6 ms |
11992 KB |
Output is correct |
11 |
Correct |
6 ms |
11988 KB |
Output is correct |
12 |
Correct |
6 ms |
12048 KB |
Output is correct |
13 |
Correct |
6 ms |
11988 KB |
Output is correct |
14 |
Correct |
6 ms |
11988 KB |
Output is correct |
15 |
Correct |
7 ms |
11988 KB |
Output is correct |
16 |
Correct |
6 ms |
11988 KB |
Output is correct |
17 |
Correct |
6 ms |
11944 KB |
Output is correct |
18 |
Correct |
6 ms |
11988 KB |
Output is correct |
19 |
Correct |
6 ms |
11988 KB |
Output is correct |
20 |
Correct |
6 ms |
11988 KB |
Output is correct |
21 |
Correct |
7 ms |
11988 KB |
Output is correct |
22 |
Correct |
8 ms |
12128 KB |
Output is correct |
23 |
Correct |
7 ms |
12108 KB |
Output is correct |
24 |
Correct |
7 ms |
12116 KB |
Output is correct |
25 |
Correct |
9 ms |
12060 KB |
Output is correct |
26 |
Correct |
9 ms |
12116 KB |
Output is correct |
27 |
Correct |
8 ms |
12116 KB |
Output is correct |
28 |
Correct |
7 ms |
12116 KB |
Output is correct |
29 |
Correct |
7 ms |
12116 KB |
Output is correct |
30 |
Correct |
6 ms |
12048 KB |
Output is correct |
31 |
Correct |
8 ms |
12116 KB |
Output is correct |
32 |
Correct |
6 ms |
11988 KB |
Output is correct |
33 |
Correct |
6 ms |
11988 KB |
Output is correct |
34 |
Correct |
7 ms |
11988 KB |
Output is correct |
35 |
Correct |
6 ms |
12000 KB |
Output is correct |
36 |
Correct |
6 ms |
12052 KB |
Output is correct |
37 |
Correct |
7 ms |
12056 KB |
Output is correct |
38 |
Correct |
7 ms |
12116 KB |
Output is correct |
39 |
Correct |
6 ms |
12048 KB |
Output is correct |
40 |
Correct |
7 ms |
11988 KB |
Output is correct |
41 |
Correct |
6 ms |
11988 KB |
Output is correct |
42 |
Correct |
7 ms |
11988 KB |
Output is correct |
43 |
Correct |
7 ms |
12048 KB |
Output is correct |
44 |
Correct |
8 ms |
11988 KB |
Output is correct |
45 |
Correct |
7 ms |
11988 KB |
Output is correct |
46 |
Correct |
7 ms |
11988 KB |
Output is correct |
47 |
Correct |
6 ms |
11988 KB |
Output is correct |
48 |
Correct |
6 ms |
12048 KB |
Output is correct |
49 |
Correct |
7 ms |
12052 KB |
Output is correct |
50 |
Correct |
6 ms |
11988 KB |
Output is correct |
51 |
Correct |
6 ms |
11988 KB |
Output is correct |
52 |
Correct |
7 ms |
11988 KB |
Output is correct |
53 |
Correct |
7 ms |
11988 KB |
Output is correct |
54 |
Correct |
7 ms |
12044 KB |
Output is correct |
55 |
Correct |
7 ms |
12044 KB |
Output is correct |
56 |
Correct |
6 ms |
11988 KB |
Output is correct |
57 |
Correct |
8 ms |
11988 KB |
Output is correct |
58 |
Correct |
8 ms |
12056 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
7 ms |
12032 KB |
Output is correct |
2 |
Correct |
6 ms |
11988 KB |
Output is correct |
3 |
Correct |
6 ms |
11932 KB |
Output is correct |
4 |
Correct |
6 ms |
12040 KB |
Output is correct |
5 |
Correct |
6 ms |
11988 KB |
Output is correct |
6 |
Correct |
6 ms |
12052 KB |
Output is correct |
7 |
Correct |
6 ms |
11988 KB |
Output is correct |
8 |
Correct |
6 ms |
12044 KB |
Output is correct |
9 |
Correct |
6 ms |
11988 KB |
Output is correct |
10 |
Correct |
6 ms |
11992 KB |
Output is correct |
11 |
Correct |
6 ms |
11988 KB |
Output is correct |
12 |
Correct |
6 ms |
12048 KB |
Output is correct |
13 |
Correct |
6 ms |
11988 KB |
Output is correct |
14 |
Correct |
6 ms |
11988 KB |
Output is correct |
15 |
Correct |
7 ms |
11988 KB |
Output is correct |
16 |
Correct |
6 ms |
11988 KB |
Output is correct |
17 |
Correct |
6 ms |
11944 KB |
Output is correct |
18 |
Correct |
6 ms |
11988 KB |
Output is correct |
19 |
Correct |
6 ms |
11988 KB |
Output is correct |
20 |
Correct |
6 ms |
11988 KB |
Output is correct |
21 |
Correct |
7 ms |
11988 KB |
Output is correct |
22 |
Correct |
8 ms |
12128 KB |
Output is correct |
23 |
Correct |
7 ms |
12108 KB |
Output is correct |
24 |
Correct |
7 ms |
12116 KB |
Output is correct |
25 |
Correct |
9 ms |
12060 KB |
Output is correct |
26 |
Correct |
9 ms |
12116 KB |
Output is correct |
27 |
Correct |
8 ms |
12116 KB |
Output is correct |
28 |
Correct |
7 ms |
12116 KB |
Output is correct |
29 |
Correct |
7 ms |
12116 KB |
Output is correct |
30 |
Correct |
6 ms |
12048 KB |
Output is correct |
31 |
Correct |
8 ms |
12116 KB |
Output is correct |
32 |
Correct |
6 ms |
11988 KB |
Output is correct |
33 |
Correct |
6 ms |
11988 KB |
Output is correct |
34 |
Correct |
7 ms |
11988 KB |
Output is correct |
35 |
Correct |
6 ms |
12000 KB |
Output is correct |
36 |
Correct |
6 ms |
12052 KB |
Output is correct |
37 |
Correct |
7 ms |
12056 KB |
Output is correct |
38 |
Correct |
7 ms |
12116 KB |
Output is correct |
39 |
Correct |
6 ms |
12048 KB |
Output is correct |
40 |
Correct |
7 ms |
11988 KB |
Output is correct |
41 |
Correct |
6 ms |
11988 KB |
Output is correct |
42 |
Correct |
7 ms |
11988 KB |
Output is correct |
43 |
Correct |
7 ms |
12048 KB |
Output is correct |
44 |
Correct |
8 ms |
11988 KB |
Output is correct |
45 |
Correct |
7 ms |
11988 KB |
Output is correct |
46 |
Correct |
7 ms |
11988 KB |
Output is correct |
47 |
Correct |
6 ms |
11988 KB |
Output is correct |
48 |
Correct |
6 ms |
12048 KB |
Output is correct |
49 |
Correct |
7 ms |
12052 KB |
Output is correct |
50 |
Correct |
6 ms |
11988 KB |
Output is correct |
51 |
Correct |
6 ms |
11988 KB |
Output is correct |
52 |
Correct |
7 ms |
11988 KB |
Output is correct |
53 |
Correct |
7 ms |
11988 KB |
Output is correct |
54 |
Correct |
7 ms |
12044 KB |
Output is correct |
55 |
Correct |
7 ms |
12044 KB |
Output is correct |
56 |
Correct |
6 ms |
11988 KB |
Output is correct |
57 |
Correct |
8 ms |
11988 KB |
Output is correct |
58 |
Correct |
8 ms |
12056 KB |
Output is correct |
59 |
Correct |
462 ms |
36052 KB |
Output is correct |
60 |
Correct |
555 ms |
38900 KB |
Output is correct |
61 |
Correct |
7 ms |
11988 KB |
Output is correct |
62 |
Correct |
7 ms |
12052 KB |
Output is correct |
63 |
Correct |
401 ms |
33552 KB |
Output is correct |
64 |
Correct |
9 ms |
12372 KB |
Output is correct |
65 |
Correct |
23 ms |
14320 KB |
Output is correct |
66 |
Correct |
173 ms |
29968 KB |
Output is correct |
67 |
Correct |
599 ms |
65612 KB |
Output is correct |
68 |
Correct |
632 ms |
53016 KB |
Output is correct |
69 |
Correct |
16 ms |
12884 KB |
Output is correct |
70 |
Correct |
138 ms |
21184 KB |
Output is correct |
71 |
Correct |
436 ms |
41916 KB |
Output is correct |
72 |
Correct |
437 ms |
40672 KB |
Output is correct |
73 |
Correct |
121 ms |
19020 KB |
Output is correct |
74 |
Correct |
540 ms |
37720 KB |
Output is correct |
75 |
Correct |
48 ms |
15140 KB |
Output is correct |
76 |
Correct |
461 ms |
41536 KB |
Output is correct |
77 |
Correct |
436 ms |
41708 KB |
Output is correct |
78 |
Correct |
46 ms |
15480 KB |
Output is correct |
79 |
Correct |
593 ms |
55384 KB |
Output is correct |
80 |
Correct |
9 ms |
12244 KB |
Output is correct |
81 |
Correct |
145 ms |
21260 KB |
Output is correct |
82 |
Correct |
489 ms |
39532 KB |
Output is correct |
83 |
Correct |
543 ms |
37708 KB |
Output is correct |
84 |
Correct |
552 ms |
37756 KB |
Output is correct |
85 |
Correct |
536 ms |
37676 KB |
Output is correct |
86 |
Correct |
535 ms |
38776 KB |
Output is correct |
87 |
Correct |
535 ms |
38824 KB |
Output is correct |