#include <bits/stdc++.h>
#include <set>
#include <map>
#include <unordered_map>
using namespace std;
#define ll long long
#define N (ll)(5e5+5)
#define NP (2097155ll)
#define M ((ll)1e9+7)
#define fi first
#define se second
ll n, ct, r;
vector<ll> v[N], k;
vector<pair<ll, ll>> ans;
void dfs(ll s, ll p) {
for (auto x : v[s]) if (x != p) dfs(x, s);
if (v[s].size() == 1) k.push_back(s);
}
int main() {
#define int ll
ios_base::sync_with_stdio(false), cin.tie(0), cout.tie(0);
cin >> n; ll a, b; for (int i = 1; i < n; i++) cin >> a >> b, v[a].push_back(b), v[b].push_back(a);
dfs(1, 0);
cout << (k.size() / 2 + (k.size() & 1)) << '\n';
if (k.size() & 1) {
cout << k.back() << ' ' << k[0] << '\n'; k.pop_back();
}
for (int i = 0; i < k.size()/2; i++) cout << k[i] << ' ' << k[i + k.size() / 2] << '\n';
}
Compilation message
net.cpp: In function 'int main()':
net.cpp:28:20: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
28 | for (int i = 0; i < k.size()/2; i++) cout << k[i] << ' ' << k[i + k.size() / 2] << '\n';
| ~~^~~~~~~~~~~~
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
7 ms |
11988 KB |
Output is correct |
2 |
Correct |
7 ms |
12068 KB |
Output is correct |
3 |
Correct |
7 ms |
11988 KB |
Output is correct |
4 |
Correct |
7 ms |
12068 KB |
Output is correct |
5 |
Correct |
9 ms |
11988 KB |
Output is correct |
6 |
Correct |
9 ms |
12056 KB |
Output is correct |
7 |
Correct |
6 ms |
12064 KB |
Output is correct |
8 |
Correct |
7 ms |
11952 KB |
Output is correct |
9 |
Correct |
7 ms |
12064 KB |
Output is correct |
10 |
Correct |
7 ms |
11988 KB |
Output is correct |
11 |
Correct |
6 ms |
12016 KB |
Output is correct |
12 |
Correct |
7 ms |
11988 KB |
Output is correct |
13 |
Correct |
7 ms |
12064 KB |
Output is correct |
14 |
Correct |
6 ms |
11972 KB |
Output is correct |
15 |
Correct |
7 ms |
11988 KB |
Output is correct |
16 |
Correct |
7 ms |
11988 KB |
Output is correct |
17 |
Correct |
6 ms |
12064 KB |
Output is correct |
18 |
Correct |
7 ms |
11988 KB |
Output is correct |
19 |
Correct |
7 ms |
12064 KB |
Output is correct |
20 |
Correct |
6 ms |
11988 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
7 ms |
11988 KB |
Output is correct |
2 |
Correct |
7 ms |
12068 KB |
Output is correct |
3 |
Correct |
7 ms |
11988 KB |
Output is correct |
4 |
Correct |
7 ms |
12068 KB |
Output is correct |
5 |
Correct |
9 ms |
11988 KB |
Output is correct |
6 |
Correct |
9 ms |
12056 KB |
Output is correct |
7 |
Correct |
6 ms |
12064 KB |
Output is correct |
8 |
Correct |
7 ms |
11952 KB |
Output is correct |
9 |
Correct |
7 ms |
12064 KB |
Output is correct |
10 |
Correct |
7 ms |
11988 KB |
Output is correct |
11 |
Correct |
6 ms |
12016 KB |
Output is correct |
12 |
Correct |
7 ms |
11988 KB |
Output is correct |
13 |
Correct |
7 ms |
12064 KB |
Output is correct |
14 |
Correct |
6 ms |
11972 KB |
Output is correct |
15 |
Correct |
7 ms |
11988 KB |
Output is correct |
16 |
Correct |
7 ms |
11988 KB |
Output is correct |
17 |
Correct |
6 ms |
12064 KB |
Output is correct |
18 |
Correct |
7 ms |
11988 KB |
Output is correct |
19 |
Correct |
7 ms |
12064 KB |
Output is correct |
20 |
Correct |
6 ms |
11988 KB |
Output is correct |
21 |
Correct |
7 ms |
11988 KB |
Output is correct |
22 |
Correct |
7 ms |
12200 KB |
Output is correct |
23 |
Correct |
9 ms |
12204 KB |
Output is correct |
24 |
Correct |
9 ms |
12116 KB |
Output is correct |
25 |
Correct |
8 ms |
12116 KB |
Output is correct |
26 |
Correct |
7 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 |
7 ms |
11988 KB |
Output is correct |
31 |
Correct |
7 ms |
12116 KB |
Output is correct |
32 |
Correct |
7 ms |
11944 KB |
Output is correct |
33 |
Correct |
7 ms |
11988 KB |
Output is correct |
34 |
Correct |
6 ms |
11988 KB |
Output is correct |
35 |
Correct |
7 ms |
11948 KB |
Output is correct |
36 |
Correct |
7 ms |
12068 KB |
Output is correct |
37 |
Correct |
7 ms |
11988 KB |
Output is correct |
38 |
Correct |
7 ms |
12116 KB |
Output is correct |
39 |
Correct |
6 ms |
11988 KB |
Output is correct |
40 |
Correct |
7 ms |
11988 KB |
Output is correct |
41 |
Correct |
8 ms |
12008 KB |
Output is correct |
42 |
Correct |
7 ms |
11988 KB |
Output is correct |
43 |
Correct |
7 ms |
12116 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 |
7 ms |
11988 KB |
Output is correct |
48 |
Correct |
7 ms |
11988 KB |
Output is correct |
49 |
Correct |
7 ms |
12116 KB |
Output is correct |
50 |
Correct |
7 ms |
12028 KB |
Output is correct |
51 |
Correct |
6 ms |
12064 KB |
Output is correct |
52 |
Correct |
7 ms |
11988 KB |
Output is correct |
53 |
Correct |
7 ms |
12068 KB |
Output is correct |
54 |
Correct |
7 ms |
11988 KB |
Output is correct |
55 |
Correct |
7 ms |
11988 KB |
Output is correct |
56 |
Correct |
6 ms |
11988 KB |
Output is correct |
57 |
Correct |
7 ms |
12064 KB |
Output is correct |
58 |
Correct |
8 ms |
12116 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
7 ms |
11988 KB |
Output is correct |
2 |
Correct |
7 ms |
12068 KB |
Output is correct |
3 |
Correct |
7 ms |
11988 KB |
Output is correct |
4 |
Correct |
7 ms |
12068 KB |
Output is correct |
5 |
Correct |
9 ms |
11988 KB |
Output is correct |
6 |
Correct |
9 ms |
12056 KB |
Output is correct |
7 |
Correct |
6 ms |
12064 KB |
Output is correct |
8 |
Correct |
7 ms |
11952 KB |
Output is correct |
9 |
Correct |
7 ms |
12064 KB |
Output is correct |
10 |
Correct |
7 ms |
11988 KB |
Output is correct |
11 |
Correct |
6 ms |
12016 KB |
Output is correct |
12 |
Correct |
7 ms |
11988 KB |
Output is correct |
13 |
Correct |
7 ms |
12064 KB |
Output is correct |
14 |
Correct |
6 ms |
11972 KB |
Output is correct |
15 |
Correct |
7 ms |
11988 KB |
Output is correct |
16 |
Correct |
7 ms |
11988 KB |
Output is correct |
17 |
Correct |
6 ms |
12064 KB |
Output is correct |
18 |
Correct |
7 ms |
11988 KB |
Output is correct |
19 |
Correct |
7 ms |
12064 KB |
Output is correct |
20 |
Correct |
6 ms |
11988 KB |
Output is correct |
21 |
Correct |
7 ms |
11988 KB |
Output is correct |
22 |
Correct |
7 ms |
12200 KB |
Output is correct |
23 |
Correct |
9 ms |
12204 KB |
Output is correct |
24 |
Correct |
9 ms |
12116 KB |
Output is correct |
25 |
Correct |
8 ms |
12116 KB |
Output is correct |
26 |
Correct |
7 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 |
7 ms |
11988 KB |
Output is correct |
31 |
Correct |
7 ms |
12116 KB |
Output is correct |
32 |
Correct |
7 ms |
11944 KB |
Output is correct |
33 |
Correct |
7 ms |
11988 KB |
Output is correct |
34 |
Correct |
6 ms |
11988 KB |
Output is correct |
35 |
Correct |
7 ms |
11948 KB |
Output is correct |
36 |
Correct |
7 ms |
12068 KB |
Output is correct |
37 |
Correct |
7 ms |
11988 KB |
Output is correct |
38 |
Correct |
7 ms |
12116 KB |
Output is correct |
39 |
Correct |
6 ms |
11988 KB |
Output is correct |
40 |
Correct |
7 ms |
11988 KB |
Output is correct |
41 |
Correct |
8 ms |
12008 KB |
Output is correct |
42 |
Correct |
7 ms |
11988 KB |
Output is correct |
43 |
Correct |
7 ms |
12116 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 |
7 ms |
11988 KB |
Output is correct |
48 |
Correct |
7 ms |
11988 KB |
Output is correct |
49 |
Correct |
7 ms |
12116 KB |
Output is correct |
50 |
Correct |
7 ms |
12028 KB |
Output is correct |
51 |
Correct |
6 ms |
12064 KB |
Output is correct |
52 |
Correct |
7 ms |
11988 KB |
Output is correct |
53 |
Correct |
7 ms |
12068 KB |
Output is correct |
54 |
Correct |
7 ms |
11988 KB |
Output is correct |
55 |
Correct |
7 ms |
11988 KB |
Output is correct |
56 |
Correct |
6 ms |
11988 KB |
Output is correct |
57 |
Correct |
7 ms |
12064 KB |
Output is correct |
58 |
Correct |
8 ms |
12116 KB |
Output is correct |
59 |
Correct |
300 ms |
37564 KB |
Output is correct |
60 |
Correct |
366 ms |
39768 KB |
Output is correct |
61 |
Correct |
7 ms |
11988 KB |
Output is correct |
62 |
Correct |
7 ms |
12064 KB |
Output is correct |
63 |
Correct |
262 ms |
34248 KB |
Output is correct |
64 |
Correct |
8 ms |
12500 KB |
Output is correct |
65 |
Correct |
15 ms |
14252 KB |
Output is correct |
66 |
Correct |
116 ms |
29712 KB |
Output is correct |
67 |
Correct |
441 ms |
47220 KB |
Output is correct |
68 |
Correct |
461 ms |
49096 KB |
Output is correct |
69 |
Correct |
11 ms |
13100 KB |
Output is correct |
70 |
Correct |
74 ms |
22808 KB |
Output is correct |
71 |
Correct |
254 ms |
42172 KB |
Output is correct |
72 |
Correct |
271 ms |
41064 KB |
Output is correct |
73 |
Correct |
81 ms |
19956 KB |
Output is correct |
74 |
Correct |
367 ms |
37604 KB |
Output is correct |
75 |
Correct |
24 ms |
15688 KB |
Output is correct |
76 |
Correct |
260 ms |
41592 KB |
Output is correct |
77 |
Correct |
250 ms |
42044 KB |
Output is correct |
78 |
Correct |
26 ms |
15820 KB |
Output is correct |
79 |
Correct |
440 ms |
45192 KB |
Output is correct |
80 |
Correct |
8 ms |
12264 KB |
Output is correct |
81 |
Correct |
88 ms |
22120 KB |
Output is correct |
82 |
Correct |
319 ms |
39948 KB |
Output is correct |
83 |
Correct |
380 ms |
37532 KB |
Output is correct |
84 |
Correct |
405 ms |
37812 KB |
Output is correct |
85 |
Correct |
388 ms |
37564 KB |
Output is correct |
86 |
Correct |
461 ms |
39852 KB |
Output is correct |
87 |
Correct |
406 ms |
39872 KB |
Output is correct |