#include <bits/stdc++.h>
#define ll long long
#define pii pair<int, int>
#define pll pair<ll, ll>
#define F first
#define S second
using namespace std;
int n, pre[500005], sz[500005], cnt;
vector<int> E[500005], leaf;
vector<pii> ans;
void dfs(int u)
{
sz[u] = (E[u].size() == 1);
for (auto v : E[u])
if(pre[u] != v)
{
pre[v] = u;
dfs(v);
sz[u] += sz[v];
}
}
void collect(int u)
{
if(E[u].size() == 1)
leaf.emplace_back(u);
for (auto v : E[u])
if(pre[u] != v)
{
pre[v] = u;
collect(v);
}
}
signed main()
{
ios::sync_with_stdio(0);
cin.tie(0), cout.tie(0);
cin >> n;
for (int i = 1; i < n; i++)
{
int u, v;
cin >> u >> v;
E[u].emplace_back(v);
E[v].emplace_back(u);
}
dfs(1);
int c = 1;
for (int i = 1; i <= n; i++)
{
bool flag = (sz[1] - sz[i] <= sz[1] / 2);
for(auto j : E[i])
if(pre[i] != j && sz[j] > sz[1] / 2)
flag = 0;
if(flag)
c = i;
}
pre[c] = 0;
collect(c);
for (int i = 0; i < sz[1] / 2; i++)
ans.emplace_back(pii(leaf[i], leaf[i + (sz[1] + 1) / 2]));
if(sz[1] & 1)
ans.emplace_back(pii(c, leaf[sz[1] / 2]));
cout << ans.size() << '\n';
for(auto [i, j] : ans)
cout << i << ' ' << j << '\n';
}
Compilation message
net.cpp: In function 'int main()':
net.cpp:67:14: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
67 | for(auto [i, j] : ans)
| ^
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
6 ms |
11988 KB |
Output is correct |
2 |
Correct |
6 ms |
11988 KB |
Output is correct |
3 |
Correct |
8 ms |
11988 KB |
Output is correct |
4 |
Correct |
6 ms |
11988 KB |
Output is correct |
5 |
Correct |
6 ms |
11988 KB |
Output is correct |
6 |
Correct |
6 ms |
11988 KB |
Output is correct |
7 |
Correct |
6 ms |
11988 KB |
Output is correct |
8 |
Correct |
6 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 |
12084 KB |
Output is correct |
13 |
Correct |
6 ms |
11984 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 |
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 |
7 ms |
11988 KB |
Output is correct |
20 |
Correct |
8 ms |
11988 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
6 ms |
11988 KB |
Output is correct |
2 |
Correct |
6 ms |
11988 KB |
Output is correct |
3 |
Correct |
8 ms |
11988 KB |
Output is correct |
4 |
Correct |
6 ms |
11988 KB |
Output is correct |
5 |
Correct |
6 ms |
11988 KB |
Output is correct |
6 |
Correct |
6 ms |
11988 KB |
Output is correct |
7 |
Correct |
6 ms |
11988 KB |
Output is correct |
8 |
Correct |
6 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 |
12084 KB |
Output is correct |
13 |
Correct |
6 ms |
11984 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 |
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 |
7 ms |
11988 KB |
Output is correct |
20 |
Correct |
8 ms |
11988 KB |
Output is correct |
21 |
Correct |
6 ms |
11988 KB |
Output is correct |
22 |
Correct |
7 ms |
12116 KB |
Output is correct |
23 |
Correct |
7 ms |
12116 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 |
12160 KB |
Output is correct |
27 |
Correct |
8 ms |
12116 KB |
Output is correct |
28 |
Correct |
7 ms |
12116 KB |
Output is correct |
29 |
Correct |
8 ms |
12116 KB |
Output is correct |
30 |
Correct |
8 ms |
11988 KB |
Output is correct |
31 |
Correct |
7 ms |
12116 KB |
Output is correct |
32 |
Correct |
6 ms |
12080 KB |
Output is correct |
33 |
Correct |
6 ms |
11988 KB |
Output is correct |
34 |
Correct |
6 ms |
12016 KB |
Output is correct |
35 |
Correct |
6 ms |
12080 KB |
Output is correct |
36 |
Correct |
6 ms |
11988 KB |
Output is correct |
37 |
Correct |
7 ms |
12116 KB |
Output is correct |
38 |
Correct |
7 ms |
12116 KB |
Output is correct |
39 |
Correct |
7 ms |
12036 KB |
Output is correct |
40 |
Correct |
7 ms |
12076 KB |
Output is correct |
41 |
Correct |
6 ms |
11988 KB |
Output is correct |
42 |
Correct |
6 ms |
11988 KB |
Output is correct |
43 |
Correct |
6 ms |
12116 KB |
Output is correct |
44 |
Correct |
6 ms |
11988 KB |
Output is correct |
45 |
Correct |
7 ms |
11988 KB |
Output is correct |
46 |
Correct |
6 ms |
12116 KB |
Output is correct |
47 |
Correct |
6 ms |
11988 KB |
Output is correct |
48 |
Correct |
7 ms |
11988 KB |
Output is correct |
49 |
Correct |
6 ms |
12116 KB |
Output is correct |
50 |
Correct |
9 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 |
6 ms |
12028 KB |
Output is correct |
55 |
Correct |
6 ms |
11988 KB |
Output is correct |
56 |
Correct |
6 ms |
12084 KB |
Output is correct |
57 |
Correct |
6 ms |
11988 KB |
Output is correct |
58 |
Correct |
7 ms |
12216 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
6 ms |
11988 KB |
Output is correct |
2 |
Correct |
6 ms |
11988 KB |
Output is correct |
3 |
Correct |
8 ms |
11988 KB |
Output is correct |
4 |
Correct |
6 ms |
11988 KB |
Output is correct |
5 |
Correct |
6 ms |
11988 KB |
Output is correct |
6 |
Correct |
6 ms |
11988 KB |
Output is correct |
7 |
Correct |
6 ms |
11988 KB |
Output is correct |
8 |
Correct |
6 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 |
12084 KB |
Output is correct |
13 |
Correct |
6 ms |
11984 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 |
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 |
7 ms |
11988 KB |
Output is correct |
20 |
Correct |
8 ms |
11988 KB |
Output is correct |
21 |
Correct |
6 ms |
11988 KB |
Output is correct |
22 |
Correct |
7 ms |
12116 KB |
Output is correct |
23 |
Correct |
7 ms |
12116 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 |
12160 KB |
Output is correct |
27 |
Correct |
8 ms |
12116 KB |
Output is correct |
28 |
Correct |
7 ms |
12116 KB |
Output is correct |
29 |
Correct |
8 ms |
12116 KB |
Output is correct |
30 |
Correct |
8 ms |
11988 KB |
Output is correct |
31 |
Correct |
7 ms |
12116 KB |
Output is correct |
32 |
Correct |
6 ms |
12080 KB |
Output is correct |
33 |
Correct |
6 ms |
11988 KB |
Output is correct |
34 |
Correct |
6 ms |
12016 KB |
Output is correct |
35 |
Correct |
6 ms |
12080 KB |
Output is correct |
36 |
Correct |
6 ms |
11988 KB |
Output is correct |
37 |
Correct |
7 ms |
12116 KB |
Output is correct |
38 |
Correct |
7 ms |
12116 KB |
Output is correct |
39 |
Correct |
7 ms |
12036 KB |
Output is correct |
40 |
Correct |
7 ms |
12076 KB |
Output is correct |
41 |
Correct |
6 ms |
11988 KB |
Output is correct |
42 |
Correct |
6 ms |
11988 KB |
Output is correct |
43 |
Correct |
6 ms |
12116 KB |
Output is correct |
44 |
Correct |
6 ms |
11988 KB |
Output is correct |
45 |
Correct |
7 ms |
11988 KB |
Output is correct |
46 |
Correct |
6 ms |
12116 KB |
Output is correct |
47 |
Correct |
6 ms |
11988 KB |
Output is correct |
48 |
Correct |
7 ms |
11988 KB |
Output is correct |
49 |
Correct |
6 ms |
12116 KB |
Output is correct |
50 |
Correct |
9 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 |
6 ms |
12028 KB |
Output is correct |
55 |
Correct |
6 ms |
11988 KB |
Output is correct |
56 |
Correct |
6 ms |
12084 KB |
Output is correct |
57 |
Correct |
6 ms |
11988 KB |
Output is correct |
58 |
Correct |
7 ms |
12216 KB |
Output is correct |
59 |
Correct |
360 ms |
40632 KB |
Output is correct |
60 |
Correct |
459 ms |
43952 KB |
Output is correct |
61 |
Correct |
6 ms |
11988 KB |
Output is correct |
62 |
Correct |
6 ms |
11988 KB |
Output is correct |
63 |
Correct |
273 ms |
37932 KB |
Output is correct |
64 |
Correct |
8 ms |
12628 KB |
Output is correct |
65 |
Correct |
16 ms |
14616 KB |
Output is correct |
66 |
Correct |
151 ms |
34588 KB |
Output is correct |
67 |
Correct |
535 ms |
61660 KB |
Output is correct |
68 |
Correct |
526 ms |
60408 KB |
Output is correct |
69 |
Correct |
11 ms |
13116 KB |
Output is correct |
70 |
Correct |
101 ms |
23060 KB |
Output is correct |
71 |
Correct |
265 ms |
47672 KB |
Output is correct |
72 |
Correct |
312 ms |
46392 KB |
Output is correct |
73 |
Correct |
87 ms |
20464 KB |
Output is correct |
74 |
Correct |
441 ms |
42612 KB |
Output is correct |
75 |
Correct |
25 ms |
15944 KB |
Output is correct |
76 |
Correct |
302 ms |
47400 KB |
Output is correct |
77 |
Correct |
276 ms |
47516 KB |
Output is correct |
78 |
Correct |
30 ms |
16340 KB |
Output is correct |
79 |
Correct |
514 ms |
56268 KB |
Output is correct |
80 |
Correct |
8 ms |
12244 KB |
Output is correct |
81 |
Correct |
94 ms |
23076 KB |
Output is correct |
82 |
Correct |
364 ms |
44852 KB |
Output is correct |
83 |
Correct |
458 ms |
42516 KB |
Output is correct |
84 |
Correct |
436 ms |
42524 KB |
Output is correct |
85 |
Correct |
426 ms |
42552 KB |
Output is correct |
86 |
Correct |
396 ms |
44000 KB |
Output is correct |
87 |
Correct |
416 ms |
43972 KB |
Output is correct |