#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define vi vector<ll>
#define pi pair<ll,ll>
#define fi first
#define se second
#define gcd __gcd
#define mset(a,v) memset(a, v, sizeof(a))
#define endl '\n'
const int N = 1e6 + 5,LOG = 27;
const ll MOD = 1e9 + 7,INF = 1e9;
ll n; vector<ll>g[N];
vector<ll>leaf; bool vis[N];
void dfs(ll u,ll p = 0){
if(g[u].size() == 1)leaf.push_back(u);
for(ll &v : g[u])
if(v != p) dfs(v,u);
}
void solve(){
cin>>n;
for(ll i = 1;i < n;++i){
ll u,v; cin>>u>>v;
g[u].push_back(v);
g[v].push_back(u);
}
dfs(1);
cout<<(leaf.size() + 1)/2<<endl;
for(ll i = 0;2*i < leaf.size();++i)
cout<<leaf[i]<<" "<<leaf[i + leaf.size()/2]<<endl;
}
signed main(){
cin.tie(0); cout.tie(0);
ios_base::sync_with_stdio(false);
ll t = 1; //cin>>t;
while(t--) solve();
cerr << endl << "Time elapsed: " << 1.0 * clock() / CLOCKS_PER_SEC << " s.\n";
}
Compilation message
net.cpp: In function 'void solve()':
net.cpp:31:22: 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]
31 | for(ll i = 0;2*i < leaf.size();++i)
| ~~~~^~~~~~~~~~~~~
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
11 ms |
23764 KB |
Output is correct |
2 |
Correct |
11 ms |
23812 KB |
Output is correct |
3 |
Correct |
11 ms |
23816 KB |
Output is correct |
4 |
Correct |
10 ms |
23764 KB |
Output is correct |
5 |
Correct |
12 ms |
23744 KB |
Output is correct |
6 |
Correct |
13 ms |
23748 KB |
Output is correct |
7 |
Correct |
11 ms |
23812 KB |
Output is correct |
8 |
Correct |
11 ms |
23816 KB |
Output is correct |
9 |
Correct |
12 ms |
23812 KB |
Output is correct |
10 |
Correct |
11 ms |
23796 KB |
Output is correct |
11 |
Correct |
11 ms |
23816 KB |
Output is correct |
12 |
Correct |
11 ms |
23808 KB |
Output is correct |
13 |
Correct |
11 ms |
23764 KB |
Output is correct |
14 |
Correct |
12 ms |
23816 KB |
Output is correct |
15 |
Correct |
11 ms |
23764 KB |
Output is correct |
16 |
Correct |
13 ms |
23744 KB |
Output is correct |
17 |
Correct |
11 ms |
23772 KB |
Output is correct |
18 |
Correct |
11 ms |
23812 KB |
Output is correct |
19 |
Correct |
11 ms |
23764 KB |
Output is correct |
20 |
Correct |
11 ms |
23812 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
11 ms |
23764 KB |
Output is correct |
2 |
Correct |
11 ms |
23812 KB |
Output is correct |
3 |
Correct |
11 ms |
23816 KB |
Output is correct |
4 |
Correct |
10 ms |
23764 KB |
Output is correct |
5 |
Correct |
12 ms |
23744 KB |
Output is correct |
6 |
Correct |
13 ms |
23748 KB |
Output is correct |
7 |
Correct |
11 ms |
23812 KB |
Output is correct |
8 |
Correct |
11 ms |
23816 KB |
Output is correct |
9 |
Correct |
12 ms |
23812 KB |
Output is correct |
10 |
Correct |
11 ms |
23796 KB |
Output is correct |
11 |
Correct |
11 ms |
23816 KB |
Output is correct |
12 |
Correct |
11 ms |
23808 KB |
Output is correct |
13 |
Correct |
11 ms |
23764 KB |
Output is correct |
14 |
Correct |
12 ms |
23816 KB |
Output is correct |
15 |
Correct |
11 ms |
23764 KB |
Output is correct |
16 |
Correct |
13 ms |
23744 KB |
Output is correct |
17 |
Correct |
11 ms |
23772 KB |
Output is correct |
18 |
Correct |
11 ms |
23812 KB |
Output is correct |
19 |
Correct |
11 ms |
23764 KB |
Output is correct |
20 |
Correct |
11 ms |
23812 KB |
Output is correct |
21 |
Correct |
11 ms |
23720 KB |
Output is correct |
22 |
Correct |
11 ms |
23952 KB |
Output is correct |
23 |
Correct |
12 ms |
23892 KB |
Output is correct |
24 |
Correct |
11 ms |
23892 KB |
Output is correct |
25 |
Correct |
12 ms |
23896 KB |
Output is correct |
26 |
Correct |
11 ms |
23844 KB |
Output is correct |
27 |
Correct |
12 ms |
23956 KB |
Output is correct |
28 |
Correct |
12 ms |
23884 KB |
Output is correct |
29 |
Correct |
13 ms |
23840 KB |
Output is correct |
30 |
Correct |
13 ms |
23892 KB |
Output is correct |
31 |
Correct |
14 ms |
23892 KB |
Output is correct |
32 |
Correct |
11 ms |
23764 KB |
Output is correct |
33 |
Correct |
11 ms |
23716 KB |
Output is correct |
34 |
Correct |
11 ms |
23820 KB |
Output is correct |
35 |
Correct |
12 ms |
23764 KB |
Output is correct |
36 |
Correct |
11 ms |
23764 KB |
Output is correct |
37 |
Correct |
13 ms |
23820 KB |
Output is correct |
38 |
Correct |
12 ms |
23764 KB |
Output is correct |
39 |
Correct |
11 ms |
23692 KB |
Output is correct |
40 |
Correct |
12 ms |
23764 KB |
Output is correct |
41 |
Correct |
12 ms |
23764 KB |
Output is correct |
42 |
Correct |
12 ms |
23764 KB |
Output is correct |
43 |
Correct |
11 ms |
23764 KB |
Output is correct |
44 |
Correct |
11 ms |
23812 KB |
Output is correct |
45 |
Correct |
11 ms |
23840 KB |
Output is correct |
46 |
Correct |
11 ms |
23764 KB |
Output is correct |
47 |
Correct |
11 ms |
23816 KB |
Output is correct |
48 |
Correct |
11 ms |
23764 KB |
Output is correct |
49 |
Correct |
11 ms |
23892 KB |
Output is correct |
50 |
Correct |
12 ms |
23764 KB |
Output is correct |
51 |
Correct |
12 ms |
23788 KB |
Output is correct |
52 |
Correct |
12 ms |
23764 KB |
Output is correct |
53 |
Correct |
12 ms |
23828 KB |
Output is correct |
54 |
Correct |
12 ms |
23696 KB |
Output is correct |
55 |
Correct |
11 ms |
23812 KB |
Output is correct |
56 |
Correct |
12 ms |
23764 KB |
Output is correct |
57 |
Correct |
11 ms |
23764 KB |
Output is correct |
58 |
Correct |
11 ms |
23956 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
11 ms |
23764 KB |
Output is correct |
2 |
Correct |
11 ms |
23812 KB |
Output is correct |
3 |
Correct |
11 ms |
23816 KB |
Output is correct |
4 |
Correct |
10 ms |
23764 KB |
Output is correct |
5 |
Correct |
12 ms |
23744 KB |
Output is correct |
6 |
Correct |
13 ms |
23748 KB |
Output is correct |
7 |
Correct |
11 ms |
23812 KB |
Output is correct |
8 |
Correct |
11 ms |
23816 KB |
Output is correct |
9 |
Correct |
12 ms |
23812 KB |
Output is correct |
10 |
Correct |
11 ms |
23796 KB |
Output is correct |
11 |
Correct |
11 ms |
23816 KB |
Output is correct |
12 |
Correct |
11 ms |
23808 KB |
Output is correct |
13 |
Correct |
11 ms |
23764 KB |
Output is correct |
14 |
Correct |
12 ms |
23816 KB |
Output is correct |
15 |
Correct |
11 ms |
23764 KB |
Output is correct |
16 |
Correct |
13 ms |
23744 KB |
Output is correct |
17 |
Correct |
11 ms |
23772 KB |
Output is correct |
18 |
Correct |
11 ms |
23812 KB |
Output is correct |
19 |
Correct |
11 ms |
23764 KB |
Output is correct |
20 |
Correct |
11 ms |
23812 KB |
Output is correct |
21 |
Correct |
11 ms |
23720 KB |
Output is correct |
22 |
Correct |
11 ms |
23952 KB |
Output is correct |
23 |
Correct |
12 ms |
23892 KB |
Output is correct |
24 |
Correct |
11 ms |
23892 KB |
Output is correct |
25 |
Correct |
12 ms |
23896 KB |
Output is correct |
26 |
Correct |
11 ms |
23844 KB |
Output is correct |
27 |
Correct |
12 ms |
23956 KB |
Output is correct |
28 |
Correct |
12 ms |
23884 KB |
Output is correct |
29 |
Correct |
13 ms |
23840 KB |
Output is correct |
30 |
Correct |
13 ms |
23892 KB |
Output is correct |
31 |
Correct |
14 ms |
23892 KB |
Output is correct |
32 |
Correct |
11 ms |
23764 KB |
Output is correct |
33 |
Correct |
11 ms |
23716 KB |
Output is correct |
34 |
Correct |
11 ms |
23820 KB |
Output is correct |
35 |
Correct |
12 ms |
23764 KB |
Output is correct |
36 |
Correct |
11 ms |
23764 KB |
Output is correct |
37 |
Correct |
13 ms |
23820 KB |
Output is correct |
38 |
Correct |
12 ms |
23764 KB |
Output is correct |
39 |
Correct |
11 ms |
23692 KB |
Output is correct |
40 |
Correct |
12 ms |
23764 KB |
Output is correct |
41 |
Correct |
12 ms |
23764 KB |
Output is correct |
42 |
Correct |
12 ms |
23764 KB |
Output is correct |
43 |
Correct |
11 ms |
23764 KB |
Output is correct |
44 |
Correct |
11 ms |
23812 KB |
Output is correct |
45 |
Correct |
11 ms |
23840 KB |
Output is correct |
46 |
Correct |
11 ms |
23764 KB |
Output is correct |
47 |
Correct |
11 ms |
23816 KB |
Output is correct |
48 |
Correct |
11 ms |
23764 KB |
Output is correct |
49 |
Correct |
11 ms |
23892 KB |
Output is correct |
50 |
Correct |
12 ms |
23764 KB |
Output is correct |
51 |
Correct |
12 ms |
23788 KB |
Output is correct |
52 |
Correct |
12 ms |
23764 KB |
Output is correct |
53 |
Correct |
12 ms |
23828 KB |
Output is correct |
54 |
Correct |
12 ms |
23696 KB |
Output is correct |
55 |
Correct |
11 ms |
23812 KB |
Output is correct |
56 |
Correct |
12 ms |
23764 KB |
Output is correct |
57 |
Correct |
11 ms |
23764 KB |
Output is correct |
58 |
Correct |
11 ms |
23956 KB |
Output is correct |
59 |
Correct |
244 ms |
52228 KB |
Output is correct |
60 |
Correct |
302 ms |
55112 KB |
Output is correct |
61 |
Correct |
12 ms |
23792 KB |
Output is correct |
62 |
Correct |
11 ms |
23792 KB |
Output is correct |
63 |
Correct |
203 ms |
48436 KB |
Output is correct |
64 |
Correct |
13 ms |
24148 KB |
Output is correct |
65 |
Correct |
18 ms |
25720 KB |
Output is correct |
66 |
Correct |
72 ms |
39648 KB |
Output is correct |
67 |
Correct |
355 ms |
58568 KB |
Output is correct |
68 |
Correct |
360 ms |
60220 KB |
Output is correct |
69 |
Correct |
16 ms |
24788 KB |
Output is correct |
70 |
Correct |
60 ms |
35008 KB |
Output is correct |
71 |
Correct |
217 ms |
57512 KB |
Output is correct |
72 |
Correct |
213 ms |
55940 KB |
Output is correct |
73 |
Correct |
61 ms |
31812 KB |
Output is correct |
74 |
Correct |
307 ms |
52900 KB |
Output is correct |
75 |
Correct |
27 ms |
27340 KB |
Output is correct |
76 |
Correct |
214 ms |
57036 KB |
Output is correct |
77 |
Correct |
215 ms |
57348 KB |
Output is correct |
78 |
Correct |
31 ms |
27340 KB |
Output is correct |
79 |
Correct |
366 ms |
56880 KB |
Output is correct |
80 |
Correct |
13 ms |
24024 KB |
Output is correct |
81 |
Correct |
69 ms |
34280 KB |
Output is correct |
82 |
Correct |
251 ms |
54952 KB |
Output is correct |
83 |
Correct |
329 ms |
52844 KB |
Output is correct |
84 |
Correct |
287 ms |
52912 KB |
Output is correct |
85 |
Correct |
297 ms |
52888 KB |
Output is correct |
86 |
Correct |
309 ms |
55128 KB |
Output is correct |
87 |
Correct |
287 ms |
55112 KB |
Output is correct |