#include <bits/stdc++.h>
#pragma GCC optimize("O3", "unroll-loops")
#define ll long long
#define int long long
#define pb push_back
#define fi first
#define se second
#define lf (id<<1)
#define rg ((id<<1)|1)
#define md ((l+r)>>1)
#define ld long double
using namespace std;
typedef pair<int,int> pii;
typedef pair<pii, int> ipii;
const int MAXN = 6e5+10;
const int INF = 1e18+10;
const int LOG = 19;
const int MOD = 1e9+7;
const int SQRT = 450;
const vector<int> NOL = {};
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
const vector<int> dx = {1, -1, 0, 0};
const vector<int> dy = {0, 0, 1, -1};
int n;
vector <int> adj[MAXN];
vector <pii> ans;
vector <int> leaf;
int root;
void dfs(int nw, int par){
if(adj[nw].size()==1) leaf.pb(nw);
for(auto nx : adj[nw]){
if(nx==par) continue;
dfs(nx, nw);
}
}
signed main(){
// ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
cin >> n;
for(int i=1; i<=n-1; i++){
int x, y; cin >> x >> y;
adj[x].pb(y); adj[y].pb(x);
}
for(int i=1; i<=n; i++){
if(adj[i].size()!=1) root = i;
}
dfs(root, 0);
int siz = leaf.size();
cout << (siz+1)/2 << '\n';
for(int i=0; i<(siz+1)/2; i++)
cout << leaf[i] << ' ' << leaf[i+siz/2] << '\n';
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
6 ms |
14428 KB |
Output is correct |
2 |
Correct |
6 ms |
14428 KB |
Output is correct |
3 |
Correct |
6 ms |
14428 KB |
Output is correct |
4 |
Correct |
6 ms |
14528 KB |
Output is correct |
5 |
Correct |
7 ms |
14424 KB |
Output is correct |
6 |
Correct |
6 ms |
14428 KB |
Output is correct |
7 |
Correct |
6 ms |
14424 KB |
Output is correct |
8 |
Correct |
6 ms |
14424 KB |
Output is correct |
9 |
Correct |
6 ms |
14428 KB |
Output is correct |
10 |
Correct |
6 ms |
14428 KB |
Output is correct |
11 |
Correct |
6 ms |
14428 KB |
Output is correct |
12 |
Correct |
5 ms |
14428 KB |
Output is correct |
13 |
Correct |
6 ms |
14428 KB |
Output is correct |
14 |
Correct |
6 ms |
14476 KB |
Output is correct |
15 |
Correct |
5 ms |
14428 KB |
Output is correct |
16 |
Correct |
5 ms |
14428 KB |
Output is correct |
17 |
Correct |
6 ms |
14468 KB |
Output is correct |
18 |
Correct |
6 ms |
14424 KB |
Output is correct |
19 |
Correct |
6 ms |
14428 KB |
Output is correct |
20 |
Correct |
5 ms |
14360 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
6 ms |
14428 KB |
Output is correct |
2 |
Correct |
6 ms |
14428 KB |
Output is correct |
3 |
Correct |
6 ms |
14428 KB |
Output is correct |
4 |
Correct |
6 ms |
14528 KB |
Output is correct |
5 |
Correct |
7 ms |
14424 KB |
Output is correct |
6 |
Correct |
6 ms |
14428 KB |
Output is correct |
7 |
Correct |
6 ms |
14424 KB |
Output is correct |
8 |
Correct |
6 ms |
14424 KB |
Output is correct |
9 |
Correct |
6 ms |
14428 KB |
Output is correct |
10 |
Correct |
6 ms |
14428 KB |
Output is correct |
11 |
Correct |
6 ms |
14428 KB |
Output is correct |
12 |
Correct |
5 ms |
14428 KB |
Output is correct |
13 |
Correct |
6 ms |
14428 KB |
Output is correct |
14 |
Correct |
6 ms |
14476 KB |
Output is correct |
15 |
Correct |
5 ms |
14428 KB |
Output is correct |
16 |
Correct |
5 ms |
14428 KB |
Output is correct |
17 |
Correct |
6 ms |
14468 KB |
Output is correct |
18 |
Correct |
6 ms |
14424 KB |
Output is correct |
19 |
Correct |
6 ms |
14428 KB |
Output is correct |
20 |
Correct |
5 ms |
14360 KB |
Output is correct |
21 |
Correct |
6 ms |
14428 KB |
Output is correct |
22 |
Correct |
8 ms |
14428 KB |
Output is correct |
23 |
Correct |
9 ms |
14428 KB |
Output is correct |
24 |
Correct |
7 ms |
14428 KB |
Output is correct |
25 |
Correct |
6 ms |
14428 KB |
Output is correct |
26 |
Correct |
6 ms |
14428 KB |
Output is correct |
27 |
Correct |
7 ms |
14568 KB |
Output is correct |
28 |
Correct |
7 ms |
14428 KB |
Output is correct |
29 |
Correct |
8 ms |
14428 KB |
Output is correct |
30 |
Correct |
7 ms |
14428 KB |
Output is correct |
31 |
Correct |
6 ms |
14424 KB |
Output is correct |
32 |
Correct |
6 ms |
14428 KB |
Output is correct |
33 |
Correct |
5 ms |
14428 KB |
Output is correct |
34 |
Correct |
6 ms |
14424 KB |
Output is correct |
35 |
Correct |
5 ms |
14488 KB |
Output is correct |
36 |
Correct |
5 ms |
14428 KB |
Output is correct |
37 |
Correct |
5 ms |
14428 KB |
Output is correct |
38 |
Correct |
6 ms |
14428 KB |
Output is correct |
39 |
Correct |
6 ms |
14428 KB |
Output is correct |
40 |
Correct |
6 ms |
14424 KB |
Output is correct |
41 |
Correct |
6 ms |
14424 KB |
Output is correct |
42 |
Correct |
6 ms |
14428 KB |
Output is correct |
43 |
Correct |
8 ms |
14424 KB |
Output is correct |
44 |
Correct |
6 ms |
14428 KB |
Output is correct |
45 |
Correct |
7 ms |
14428 KB |
Output is correct |
46 |
Correct |
6 ms |
14428 KB |
Output is correct |
47 |
Correct |
6 ms |
14428 KB |
Output is correct |
48 |
Correct |
5 ms |
14428 KB |
Output is correct |
49 |
Correct |
6 ms |
14428 KB |
Output is correct |
50 |
Correct |
7 ms |
14428 KB |
Output is correct |
51 |
Correct |
6 ms |
14428 KB |
Output is correct |
52 |
Correct |
6 ms |
14428 KB |
Output is correct |
53 |
Correct |
6 ms |
14584 KB |
Output is correct |
54 |
Correct |
6 ms |
14428 KB |
Output is correct |
55 |
Correct |
6 ms |
14428 KB |
Output is correct |
56 |
Correct |
6 ms |
14316 KB |
Output is correct |
57 |
Correct |
6 ms |
14568 KB |
Output is correct |
58 |
Correct |
7 ms |
14428 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
6 ms |
14428 KB |
Output is correct |
2 |
Correct |
6 ms |
14428 KB |
Output is correct |
3 |
Correct |
6 ms |
14428 KB |
Output is correct |
4 |
Correct |
6 ms |
14528 KB |
Output is correct |
5 |
Correct |
7 ms |
14424 KB |
Output is correct |
6 |
Correct |
6 ms |
14428 KB |
Output is correct |
7 |
Correct |
6 ms |
14424 KB |
Output is correct |
8 |
Correct |
6 ms |
14424 KB |
Output is correct |
9 |
Correct |
6 ms |
14428 KB |
Output is correct |
10 |
Correct |
6 ms |
14428 KB |
Output is correct |
11 |
Correct |
6 ms |
14428 KB |
Output is correct |
12 |
Correct |
5 ms |
14428 KB |
Output is correct |
13 |
Correct |
6 ms |
14428 KB |
Output is correct |
14 |
Correct |
6 ms |
14476 KB |
Output is correct |
15 |
Correct |
5 ms |
14428 KB |
Output is correct |
16 |
Correct |
5 ms |
14428 KB |
Output is correct |
17 |
Correct |
6 ms |
14468 KB |
Output is correct |
18 |
Correct |
6 ms |
14424 KB |
Output is correct |
19 |
Correct |
6 ms |
14428 KB |
Output is correct |
20 |
Correct |
5 ms |
14360 KB |
Output is correct |
21 |
Correct |
6 ms |
14428 KB |
Output is correct |
22 |
Correct |
8 ms |
14428 KB |
Output is correct |
23 |
Correct |
9 ms |
14428 KB |
Output is correct |
24 |
Correct |
7 ms |
14428 KB |
Output is correct |
25 |
Correct |
6 ms |
14428 KB |
Output is correct |
26 |
Correct |
6 ms |
14428 KB |
Output is correct |
27 |
Correct |
7 ms |
14568 KB |
Output is correct |
28 |
Correct |
7 ms |
14428 KB |
Output is correct |
29 |
Correct |
8 ms |
14428 KB |
Output is correct |
30 |
Correct |
7 ms |
14428 KB |
Output is correct |
31 |
Correct |
6 ms |
14424 KB |
Output is correct |
32 |
Correct |
6 ms |
14428 KB |
Output is correct |
33 |
Correct |
5 ms |
14428 KB |
Output is correct |
34 |
Correct |
6 ms |
14424 KB |
Output is correct |
35 |
Correct |
5 ms |
14488 KB |
Output is correct |
36 |
Correct |
5 ms |
14428 KB |
Output is correct |
37 |
Correct |
5 ms |
14428 KB |
Output is correct |
38 |
Correct |
6 ms |
14428 KB |
Output is correct |
39 |
Correct |
6 ms |
14428 KB |
Output is correct |
40 |
Correct |
6 ms |
14424 KB |
Output is correct |
41 |
Correct |
6 ms |
14424 KB |
Output is correct |
42 |
Correct |
6 ms |
14428 KB |
Output is correct |
43 |
Correct |
8 ms |
14424 KB |
Output is correct |
44 |
Correct |
6 ms |
14428 KB |
Output is correct |
45 |
Correct |
7 ms |
14428 KB |
Output is correct |
46 |
Correct |
6 ms |
14428 KB |
Output is correct |
47 |
Correct |
6 ms |
14428 KB |
Output is correct |
48 |
Correct |
5 ms |
14428 KB |
Output is correct |
49 |
Correct |
6 ms |
14428 KB |
Output is correct |
50 |
Correct |
7 ms |
14428 KB |
Output is correct |
51 |
Correct |
6 ms |
14428 KB |
Output is correct |
52 |
Correct |
6 ms |
14428 KB |
Output is correct |
53 |
Correct |
6 ms |
14584 KB |
Output is correct |
54 |
Correct |
6 ms |
14428 KB |
Output is correct |
55 |
Correct |
6 ms |
14428 KB |
Output is correct |
56 |
Correct |
6 ms |
14316 KB |
Output is correct |
57 |
Correct |
6 ms |
14568 KB |
Output is correct |
58 |
Correct |
7 ms |
14428 KB |
Output is correct |
59 |
Correct |
349 ms |
42816 KB |
Output is correct |
60 |
Correct |
312 ms |
45752 KB |
Output is correct |
61 |
Correct |
6 ms |
14424 KB |
Output is correct |
62 |
Correct |
6 ms |
14368 KB |
Output is correct |
63 |
Correct |
258 ms |
39060 KB |
Output is correct |
64 |
Correct |
10 ms |
14684 KB |
Output is correct |
65 |
Correct |
17 ms |
15964 KB |
Output is correct |
66 |
Correct |
94 ms |
26448 KB |
Output is correct |
67 |
Correct |
394 ms |
55892 KB |
Output is correct |
68 |
Correct |
377 ms |
50892 KB |
Output is correct |
69 |
Correct |
12 ms |
15452 KB |
Output is correct |
70 |
Correct |
82 ms |
25680 KB |
Output is correct |
71 |
Correct |
254 ms |
48176 KB |
Output is correct |
72 |
Correct |
319 ms |
46656 KB |
Output is correct |
73 |
Correct |
66 ms |
22472 KB |
Output is correct |
74 |
Correct |
317 ms |
43468 KB |
Output is correct |
75 |
Correct |
31 ms |
18072 KB |
Output is correct |
76 |
Correct |
296 ms |
47784 KB |
Output is correct |
77 |
Correct |
285 ms |
48040 KB |
Output is correct |
78 |
Correct |
32 ms |
17868 KB |
Output is correct |
79 |
Correct |
349 ms |
45376 KB |
Output is correct |
80 |
Correct |
8 ms |
14936 KB |
Output is correct |
81 |
Correct |
92 ms |
24908 KB |
Output is correct |
82 |
Correct |
303 ms |
45628 KB |
Output is correct |
83 |
Correct |
331 ms |
43460 KB |
Output is correct |
84 |
Correct |
317 ms |
43464 KB |
Output is correct |
85 |
Correct |
342 ms |
43464 KB |
Output is correct |
86 |
Correct |
362 ms |
45688 KB |
Output is correct |
87 |
Correct |
349 ms |
46008 KB |
Output is correct |