#include <bits/stdc++.h>
using namespace std;
#define rep(i,s,e) for (int i = s; i <= e; ++i)
#define rrep(i,s,e) for (int i = s; i >= e; --i)
#define pb push_back
#define pf push_front
#define fi first
#define se second
#define all(a) a.begin(), a.end()
#define SZ(a) (int)a.size()
typedef long long ll;
typedef pair<int, int> ii;
typedef vector<ii> vii;
typedef vector<int> vi;
typedef vector<double> vd;
typedef vector<string> vs;
typedef vector<ll> vll;
const int mx = 5e5;
vi adj[mx+1], leaves;
int x;
void dfs (int u, int p) {
if (SZ(adj[u])==1) leaves.pb(u);
else x = u;
for (int v : adj[u]) {
if (v==p) continue;
dfs (v,u);
}
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
int n; cin >> n;
rep (i,1,n-1) {
int u, v; cin >> u >> v;
adj[u].pb(v);
adj[v].pb(u);
}
dfs (1,-1);
int m = leaves.size();
cout << (m+1)/2 << "\n";
rep (i,0,m/2-1) {
cout << leaves[i] << " " << leaves[i+m/2] << "\n";
}
if (m%2) cout << leaves[m-1] << " " << leaves[m/2] << "\n";
return 0;
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
7 ms |
11988 KB |
Output is correct |
2 |
Correct |
6 ms |
11988 KB |
Output is correct |
3 |
Correct |
6 ms |
11988 KB |
Output is correct |
4 |
Correct |
6 ms |
12060 KB |
Output is correct |
5 |
Correct |
6 ms |
11988 KB |
Output is correct |
6 |
Correct |
6 ms |
12064 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 |
11996 KB |
Output is correct |
10 |
Correct |
7 ms |
11988 KB |
Output is correct |
11 |
Correct |
7 ms |
12064 KB |
Output is correct |
12 |
Correct |
7 ms |
12064 KB |
Output is correct |
13 |
Correct |
7 ms |
12060 KB |
Output is correct |
14 |
Correct |
7 ms |
11988 KB |
Output is correct |
15 |
Correct |
7 ms |
12064 KB |
Output is correct |
16 |
Correct |
7 ms |
11972 KB |
Output is correct |
17 |
Correct |
6 ms |
11988 KB |
Output is correct |
18 |
Correct |
7 ms |
12064 KB |
Output is correct |
19 |
Correct |
7 ms |
11988 KB |
Output is correct |
20 |
Correct |
7 ms |
11988 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
7 ms |
11988 KB |
Output is correct |
2 |
Correct |
6 ms |
11988 KB |
Output is correct |
3 |
Correct |
6 ms |
11988 KB |
Output is correct |
4 |
Correct |
6 ms |
12060 KB |
Output is correct |
5 |
Correct |
6 ms |
11988 KB |
Output is correct |
6 |
Correct |
6 ms |
12064 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 |
11996 KB |
Output is correct |
10 |
Correct |
7 ms |
11988 KB |
Output is correct |
11 |
Correct |
7 ms |
12064 KB |
Output is correct |
12 |
Correct |
7 ms |
12064 KB |
Output is correct |
13 |
Correct |
7 ms |
12060 KB |
Output is correct |
14 |
Correct |
7 ms |
11988 KB |
Output is correct |
15 |
Correct |
7 ms |
12064 KB |
Output is correct |
16 |
Correct |
7 ms |
11972 KB |
Output is correct |
17 |
Correct |
6 ms |
11988 KB |
Output is correct |
18 |
Correct |
7 ms |
12064 KB |
Output is correct |
19 |
Correct |
7 ms |
11988 KB |
Output is correct |
20 |
Correct |
7 ms |
11988 KB |
Output is correct |
21 |
Correct |
8 ms |
11988 KB |
Output is correct |
22 |
Correct |
8 ms |
12076 KB |
Output is correct |
23 |
Correct |
8 ms |
12140 KB |
Output is correct |
24 |
Correct |
8 ms |
12116 KB |
Output is correct |
25 |
Correct |
9 ms |
12116 KB |
Output is correct |
26 |
Correct |
7 ms |
12072 KB |
Output is correct |
27 |
Correct |
8 ms |
12076 KB |
Output is correct |
28 |
Correct |
8 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 |
9 ms |
12116 KB |
Output is correct |
32 |
Correct |
6 ms |
12016 KB |
Output is correct |
33 |
Correct |
7 ms |
11988 KB |
Output is correct |
34 |
Correct |
7 ms |
12068 KB |
Output is correct |
35 |
Correct |
6 ms |
11988 KB |
Output is correct |
36 |
Correct |
7 ms |
11988 KB |
Output is correct |
37 |
Correct |
7 ms |
12068 KB |
Output is correct |
38 |
Correct |
7 ms |
12116 KB |
Output is correct |
39 |
Correct |
6 ms |
12068 KB |
Output is correct |
40 |
Correct |
7 ms |
11988 KB |
Output is correct |
41 |
Correct |
8 ms |
12064 KB |
Output is correct |
42 |
Correct |
6 ms |
11988 KB |
Output is correct |
43 |
Correct |
7 ms |
12116 KB |
Output is correct |
44 |
Correct |
6 ms |
11988 KB |
Output is correct |
45 |
Correct |
9 ms |
11988 KB |
Output is correct |
46 |
Correct |
7 ms |
11988 KB |
Output is correct |
47 |
Correct |
7 ms |
12064 KB |
Output is correct |
48 |
Correct |
9 ms |
11988 KB |
Output is correct |
49 |
Correct |
9 ms |
12084 KB |
Output is correct |
50 |
Correct |
6 ms |
12056 KB |
Output is correct |
51 |
Correct |
6 ms |
11988 KB |
Output is correct |
52 |
Correct |
6 ms |
11988 KB |
Output is correct |
53 |
Correct |
8 ms |
12116 KB |
Output is correct |
54 |
Correct |
7 ms |
12068 KB |
Output is correct |
55 |
Correct |
7 ms |
11988 KB |
Output is correct |
56 |
Correct |
7 ms |
12060 KB |
Output is correct |
57 |
Correct |
7 ms |
11988 KB |
Output is correct |
58 |
Correct |
7 ms |
12080 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
7 ms |
11988 KB |
Output is correct |
2 |
Correct |
6 ms |
11988 KB |
Output is correct |
3 |
Correct |
6 ms |
11988 KB |
Output is correct |
4 |
Correct |
6 ms |
12060 KB |
Output is correct |
5 |
Correct |
6 ms |
11988 KB |
Output is correct |
6 |
Correct |
6 ms |
12064 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 |
11996 KB |
Output is correct |
10 |
Correct |
7 ms |
11988 KB |
Output is correct |
11 |
Correct |
7 ms |
12064 KB |
Output is correct |
12 |
Correct |
7 ms |
12064 KB |
Output is correct |
13 |
Correct |
7 ms |
12060 KB |
Output is correct |
14 |
Correct |
7 ms |
11988 KB |
Output is correct |
15 |
Correct |
7 ms |
12064 KB |
Output is correct |
16 |
Correct |
7 ms |
11972 KB |
Output is correct |
17 |
Correct |
6 ms |
11988 KB |
Output is correct |
18 |
Correct |
7 ms |
12064 KB |
Output is correct |
19 |
Correct |
7 ms |
11988 KB |
Output is correct |
20 |
Correct |
7 ms |
11988 KB |
Output is correct |
21 |
Correct |
8 ms |
11988 KB |
Output is correct |
22 |
Correct |
8 ms |
12076 KB |
Output is correct |
23 |
Correct |
8 ms |
12140 KB |
Output is correct |
24 |
Correct |
8 ms |
12116 KB |
Output is correct |
25 |
Correct |
9 ms |
12116 KB |
Output is correct |
26 |
Correct |
7 ms |
12072 KB |
Output is correct |
27 |
Correct |
8 ms |
12076 KB |
Output is correct |
28 |
Correct |
8 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 |
9 ms |
12116 KB |
Output is correct |
32 |
Correct |
6 ms |
12016 KB |
Output is correct |
33 |
Correct |
7 ms |
11988 KB |
Output is correct |
34 |
Correct |
7 ms |
12068 KB |
Output is correct |
35 |
Correct |
6 ms |
11988 KB |
Output is correct |
36 |
Correct |
7 ms |
11988 KB |
Output is correct |
37 |
Correct |
7 ms |
12068 KB |
Output is correct |
38 |
Correct |
7 ms |
12116 KB |
Output is correct |
39 |
Correct |
6 ms |
12068 KB |
Output is correct |
40 |
Correct |
7 ms |
11988 KB |
Output is correct |
41 |
Correct |
8 ms |
12064 KB |
Output is correct |
42 |
Correct |
6 ms |
11988 KB |
Output is correct |
43 |
Correct |
7 ms |
12116 KB |
Output is correct |
44 |
Correct |
6 ms |
11988 KB |
Output is correct |
45 |
Correct |
9 ms |
11988 KB |
Output is correct |
46 |
Correct |
7 ms |
11988 KB |
Output is correct |
47 |
Correct |
7 ms |
12064 KB |
Output is correct |
48 |
Correct |
9 ms |
11988 KB |
Output is correct |
49 |
Correct |
9 ms |
12084 KB |
Output is correct |
50 |
Correct |
6 ms |
12056 KB |
Output is correct |
51 |
Correct |
6 ms |
11988 KB |
Output is correct |
52 |
Correct |
6 ms |
11988 KB |
Output is correct |
53 |
Correct |
8 ms |
12116 KB |
Output is correct |
54 |
Correct |
7 ms |
12068 KB |
Output is correct |
55 |
Correct |
7 ms |
11988 KB |
Output is correct |
56 |
Correct |
7 ms |
12060 KB |
Output is correct |
57 |
Correct |
7 ms |
11988 KB |
Output is correct |
58 |
Correct |
7 ms |
12080 KB |
Output is correct |
59 |
Correct |
303 ms |
35960 KB |
Output is correct |
60 |
Correct |
393 ms |
38860 KB |
Output is correct |
61 |
Correct |
6 ms |
11988 KB |
Output is correct |
62 |
Correct |
7 ms |
11940 KB |
Output is correct |
63 |
Correct |
302 ms |
33668 KB |
Output is correct |
64 |
Correct |
9 ms |
12372 KB |
Output is correct |
65 |
Correct |
15 ms |
13884 KB |
Output is correct |
66 |
Correct |
139 ms |
27888 KB |
Output is correct |
67 |
Correct |
406 ms |
46796 KB |
Output is correct |
68 |
Correct |
425 ms |
47704 KB |
Output is correct |
69 |
Correct |
11 ms |
12884 KB |
Output is correct |
70 |
Correct |
73 ms |
21216 KB |
Output is correct |
71 |
Correct |
261 ms |
41896 KB |
Output is correct |
72 |
Correct |
296 ms |
40652 KB |
Output is correct |
73 |
Correct |
96 ms |
19020 KB |
Output is correct |
74 |
Correct |
373 ms |
37648 KB |
Output is correct |
75 |
Correct |
26 ms |
15180 KB |
Output is correct |
76 |
Correct |
284 ms |
41492 KB |
Output is correct |
77 |
Correct |
278 ms |
41636 KB |
Output is correct |
78 |
Correct |
30 ms |
15308 KB |
Output is correct |
79 |
Correct |
428 ms |
45288 KB |
Output is correct |
80 |
Correct |
8 ms |
12204 KB |
Output is correct |
81 |
Correct |
86 ms |
21260 KB |
Output is correct |
82 |
Correct |
373 ms |
39624 KB |
Output is correct |
83 |
Correct |
392 ms |
37664 KB |
Output is correct |
84 |
Correct |
347 ms |
37696 KB |
Output is correct |
85 |
Correct |
379 ms |
37656 KB |
Output is correct |
86 |
Correct |
395 ms |
38700 KB |
Output is correct |
87 |
Correct |
355 ms |
38792 KB |
Output is correct |