#include<bits/stdc++.h>
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2")
using namespace std;
using ll = long long;
using pii = pair<int,int>;
using pll = pair<ll,ll>;
#define pb push_back
#define F first
#define S second
#define len(x) (int)x.size()
#define all(x) x.begin(),x.end()
#define file freopen("matrix.txt", "r", stdin);freopen("a.out", "w", stdout);
#define kill(x) {cout << x << '\n'; continue;}
#define int long long
#define double long double
const int maxn = 5e5 + 5, LG = 20, MOD = 1e9+7;// 998244353
const ll inf = 1061109567;
//priority_queue< pii , vector<pii> , greater<pii> pq;
int n;
vector<int> g[maxn], l;
void dfs(int v = 1, int par = 0) {
if(len(g[v]) == 1) l.pb(v);
for(int u : g[v]) if(u ^ par) dfs(u, v);
}
signed main() {
ios::sync_with_stdio(0), cin.tie(0);
cin >> n;
for(int i =0; i<n-1; ++i) {
int v, u;
cin >> v >> u;
g[v].pb(u);
g[u].pb(v);
}
dfs();
int t = (len(l) + 1)/2;
cout << t << '\n';
for(int i = 0; i < t; ++i)
cout << l[i] << ' ' << l[i+len(l)/2] << '\n';
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
3 ms |
12124 KB |
Output is correct |
2 |
Correct |
3 ms |
12124 KB |
Output is correct |
3 |
Correct |
4 ms |
12124 KB |
Output is correct |
4 |
Correct |
4 ms |
12148 KB |
Output is correct |
5 |
Correct |
3 ms |
12376 KB |
Output is correct |
6 |
Correct |
4 ms |
12120 KB |
Output is correct |
7 |
Correct |
5 ms |
12124 KB |
Output is correct |
8 |
Correct |
4 ms |
12124 KB |
Output is correct |
9 |
Correct |
3 ms |
12144 KB |
Output is correct |
10 |
Correct |
4 ms |
12124 KB |
Output is correct |
11 |
Correct |
4 ms |
12120 KB |
Output is correct |
12 |
Correct |
4 ms |
12140 KB |
Output is correct |
13 |
Correct |
4 ms |
12124 KB |
Output is correct |
14 |
Correct |
4 ms |
12120 KB |
Output is correct |
15 |
Correct |
3 ms |
12124 KB |
Output is correct |
16 |
Correct |
3 ms |
12124 KB |
Output is correct |
17 |
Correct |
4 ms |
12120 KB |
Output is correct |
18 |
Correct |
3 ms |
12124 KB |
Output is correct |
19 |
Correct |
3 ms |
12120 KB |
Output is correct |
20 |
Correct |
4 ms |
12124 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
3 ms |
12124 KB |
Output is correct |
2 |
Correct |
3 ms |
12124 KB |
Output is correct |
3 |
Correct |
4 ms |
12124 KB |
Output is correct |
4 |
Correct |
4 ms |
12148 KB |
Output is correct |
5 |
Correct |
3 ms |
12376 KB |
Output is correct |
6 |
Correct |
4 ms |
12120 KB |
Output is correct |
7 |
Correct |
5 ms |
12124 KB |
Output is correct |
8 |
Correct |
4 ms |
12124 KB |
Output is correct |
9 |
Correct |
3 ms |
12144 KB |
Output is correct |
10 |
Correct |
4 ms |
12124 KB |
Output is correct |
11 |
Correct |
4 ms |
12120 KB |
Output is correct |
12 |
Correct |
4 ms |
12140 KB |
Output is correct |
13 |
Correct |
4 ms |
12124 KB |
Output is correct |
14 |
Correct |
4 ms |
12120 KB |
Output is correct |
15 |
Correct |
3 ms |
12124 KB |
Output is correct |
16 |
Correct |
3 ms |
12124 KB |
Output is correct |
17 |
Correct |
4 ms |
12120 KB |
Output is correct |
18 |
Correct |
3 ms |
12124 KB |
Output is correct |
19 |
Correct |
3 ms |
12120 KB |
Output is correct |
20 |
Correct |
4 ms |
12124 KB |
Output is correct |
21 |
Correct |
3 ms |
12124 KB |
Output is correct |
22 |
Correct |
4 ms |
12124 KB |
Output is correct |
23 |
Correct |
5 ms |
12120 KB |
Output is correct |
24 |
Correct |
4 ms |
12120 KB |
Output is correct |
25 |
Correct |
4 ms |
12120 KB |
Output is correct |
26 |
Correct |
4 ms |
12124 KB |
Output is correct |
27 |
Correct |
5 ms |
12120 KB |
Output is correct |
28 |
Correct |
4 ms |
12124 KB |
Output is correct |
29 |
Correct |
4 ms |
12120 KB |
Output is correct |
30 |
Correct |
3 ms |
12124 KB |
Output is correct |
31 |
Correct |
5 ms |
12124 KB |
Output is correct |
32 |
Correct |
3 ms |
12124 KB |
Output is correct |
33 |
Correct |
3 ms |
12124 KB |
Output is correct |
34 |
Correct |
3 ms |
12124 KB |
Output is correct |
35 |
Correct |
4 ms |
12124 KB |
Output is correct |
36 |
Correct |
3 ms |
12120 KB |
Output is correct |
37 |
Correct |
4 ms |
12120 KB |
Output is correct |
38 |
Correct |
3 ms |
12124 KB |
Output is correct |
39 |
Correct |
4 ms |
12124 KB |
Output is correct |
40 |
Correct |
3 ms |
12124 KB |
Output is correct |
41 |
Correct |
4 ms |
12124 KB |
Output is correct |
42 |
Correct |
3 ms |
12124 KB |
Output is correct |
43 |
Correct |
4 ms |
12376 KB |
Output is correct |
44 |
Correct |
3 ms |
12120 KB |
Output is correct |
45 |
Correct |
3 ms |
12120 KB |
Output is correct |
46 |
Correct |
5 ms |
12124 KB |
Output is correct |
47 |
Correct |
3 ms |
12120 KB |
Output is correct |
48 |
Correct |
3 ms |
12124 KB |
Output is correct |
49 |
Correct |
3 ms |
12124 KB |
Output is correct |
50 |
Correct |
3 ms |
12124 KB |
Output is correct |
51 |
Correct |
3 ms |
12124 KB |
Output is correct |
52 |
Correct |
3 ms |
12120 KB |
Output is correct |
53 |
Correct |
3 ms |
12120 KB |
Output is correct |
54 |
Correct |
4 ms |
12124 KB |
Output is correct |
55 |
Correct |
4 ms |
12132 KB |
Output is correct |
56 |
Correct |
4 ms |
12124 KB |
Output is correct |
57 |
Correct |
3 ms |
12120 KB |
Output is correct |
58 |
Correct |
4 ms |
12124 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
3 ms |
12124 KB |
Output is correct |
2 |
Correct |
3 ms |
12124 KB |
Output is correct |
3 |
Correct |
4 ms |
12124 KB |
Output is correct |
4 |
Correct |
4 ms |
12148 KB |
Output is correct |
5 |
Correct |
3 ms |
12376 KB |
Output is correct |
6 |
Correct |
4 ms |
12120 KB |
Output is correct |
7 |
Correct |
5 ms |
12124 KB |
Output is correct |
8 |
Correct |
4 ms |
12124 KB |
Output is correct |
9 |
Correct |
3 ms |
12144 KB |
Output is correct |
10 |
Correct |
4 ms |
12124 KB |
Output is correct |
11 |
Correct |
4 ms |
12120 KB |
Output is correct |
12 |
Correct |
4 ms |
12140 KB |
Output is correct |
13 |
Correct |
4 ms |
12124 KB |
Output is correct |
14 |
Correct |
4 ms |
12120 KB |
Output is correct |
15 |
Correct |
3 ms |
12124 KB |
Output is correct |
16 |
Correct |
3 ms |
12124 KB |
Output is correct |
17 |
Correct |
4 ms |
12120 KB |
Output is correct |
18 |
Correct |
3 ms |
12124 KB |
Output is correct |
19 |
Correct |
3 ms |
12120 KB |
Output is correct |
20 |
Correct |
4 ms |
12124 KB |
Output is correct |
21 |
Correct |
3 ms |
12124 KB |
Output is correct |
22 |
Correct |
4 ms |
12124 KB |
Output is correct |
23 |
Correct |
5 ms |
12120 KB |
Output is correct |
24 |
Correct |
4 ms |
12120 KB |
Output is correct |
25 |
Correct |
4 ms |
12120 KB |
Output is correct |
26 |
Correct |
4 ms |
12124 KB |
Output is correct |
27 |
Correct |
5 ms |
12120 KB |
Output is correct |
28 |
Correct |
4 ms |
12124 KB |
Output is correct |
29 |
Correct |
4 ms |
12120 KB |
Output is correct |
30 |
Correct |
3 ms |
12124 KB |
Output is correct |
31 |
Correct |
5 ms |
12124 KB |
Output is correct |
32 |
Correct |
3 ms |
12124 KB |
Output is correct |
33 |
Correct |
3 ms |
12124 KB |
Output is correct |
34 |
Correct |
3 ms |
12124 KB |
Output is correct |
35 |
Correct |
4 ms |
12124 KB |
Output is correct |
36 |
Correct |
3 ms |
12120 KB |
Output is correct |
37 |
Correct |
4 ms |
12120 KB |
Output is correct |
38 |
Correct |
3 ms |
12124 KB |
Output is correct |
39 |
Correct |
4 ms |
12124 KB |
Output is correct |
40 |
Correct |
3 ms |
12124 KB |
Output is correct |
41 |
Correct |
4 ms |
12124 KB |
Output is correct |
42 |
Correct |
3 ms |
12124 KB |
Output is correct |
43 |
Correct |
4 ms |
12376 KB |
Output is correct |
44 |
Correct |
3 ms |
12120 KB |
Output is correct |
45 |
Correct |
3 ms |
12120 KB |
Output is correct |
46 |
Correct |
5 ms |
12124 KB |
Output is correct |
47 |
Correct |
3 ms |
12120 KB |
Output is correct |
48 |
Correct |
3 ms |
12124 KB |
Output is correct |
49 |
Correct |
3 ms |
12124 KB |
Output is correct |
50 |
Correct |
3 ms |
12124 KB |
Output is correct |
51 |
Correct |
3 ms |
12124 KB |
Output is correct |
52 |
Correct |
3 ms |
12120 KB |
Output is correct |
53 |
Correct |
3 ms |
12120 KB |
Output is correct |
54 |
Correct |
4 ms |
12124 KB |
Output is correct |
55 |
Correct |
4 ms |
12132 KB |
Output is correct |
56 |
Correct |
4 ms |
12124 KB |
Output is correct |
57 |
Correct |
3 ms |
12120 KB |
Output is correct |
58 |
Correct |
4 ms |
12124 KB |
Output is correct |
59 |
Correct |
276 ms |
35528 KB |
Output is correct |
60 |
Correct |
344 ms |
37160 KB |
Output is correct |
61 |
Correct |
3 ms |
12120 KB |
Output is correct |
62 |
Correct |
3 ms |
12120 KB |
Output is correct |
63 |
Correct |
205 ms |
32536 KB |
Output is correct |
64 |
Correct |
4 ms |
12376 KB |
Output is correct |
65 |
Correct |
10 ms |
13688 KB |
Output is correct |
66 |
Correct |
106 ms |
24212 KB |
Output is correct |
67 |
Correct |
378 ms |
38216 KB |
Output is correct |
68 |
Correct |
347 ms |
39436 KB |
Output is correct |
69 |
Correct |
7 ms |
13144 KB |
Output is correct |
70 |
Correct |
51 ms |
21316 KB |
Output is correct |
71 |
Correct |
180 ms |
39352 KB |
Output is correct |
72 |
Correct |
197 ms |
38840 KB |
Output is correct |
73 |
Correct |
48 ms |
18332 KB |
Output is correct |
74 |
Correct |
296 ms |
34584 KB |
Output is correct |
75 |
Correct |
17 ms |
15056 KB |
Output is correct |
76 |
Correct |
198 ms |
38676 KB |
Output is correct |
77 |
Correct |
189 ms |
39156 KB |
Output is correct |
78 |
Correct |
18 ms |
14940 KB |
Output is correct |
79 |
Correct |
315 ms |
36432 KB |
Output is correct |
80 |
Correct |
4 ms |
12376 KB |
Output is correct |
81 |
Correct |
55 ms |
20616 KB |
Output is correct |
82 |
Correct |
228 ms |
37200 KB |
Output is correct |
83 |
Correct |
295 ms |
34504 KB |
Output is correct |
84 |
Correct |
283 ms |
34752 KB |
Output is correct |
85 |
Correct |
280 ms |
34472 KB |
Output is correct |
86 |
Correct |
302 ms |
37904 KB |
Output is correct |
87 |
Correct |
262 ms |
37816 KB |
Output is correct |