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Submission #394674

# Submission time Handle Problem Language Result Execution time Memory
394674 2021-04-27T07:21:51 Z ali_tavakoli Network (BOI15_net) C++14
100 / 100
 508 ms 45300 KB 
//In The Name Of Allah
#include<bits/stdc++.h>
using namespace std;
	
typedef long long ll;
#define pb push_back
#define F first
#define S second
//#pragma GCC optimize("Ofast")
	
const int maxn = 5e5 + 5;
	
int n, st;
vector<int> adj[maxn], leaf;
	
void dfs(int v, int p = 0)
{
	if(adj[v].size() == 1)
		leaf.pb(v);
	for(auto u : adj[v])
		if(u != p)
			dfs(u, v);
}
	
int main()
{
	ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
	cin >> n;
	for(int i = 0; i < n - 1; i++)
	{
		int a, b;
		cin >> a >> b;
		adj[a].pb(b);
		adj[b].pb(a);
	}
	
	for(int i = 1; i <= n; i++)
		if(adj[i].size() > 1)
		{
			dfs(i);
			st = i;
			break;
		}
	
	cout << (leaf.size() + 1) / 2 << '\n';
	int last;
	//cout << leaf.size() << '\n';
	//return 0;
	
	for(int i = 0; i + leaf.size() / 2 < leaf.size(); i ++)
	{
		cout << leaf[i] << " " << leaf[i + leaf.size() / 2] << '\n';
		last = i + leaf.size() / 2;
	}

	if(last != leaf.size() - 1)
		cout << leaf[leaf.size() - 1] << " " << st << '\n';
}
	
/*
6
1 2
2 3
2 4
5 4
6 4
	
8
1 2
2 3
3 4
4 5
3 6
3 7
3 8
*/

Compilation message

net.cpp: In function 'int main()':
net.cpp:56:10: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   56 |  if(last != leaf.size() - 1)
      |     ~~~~~^~~~~~~~~~~~~~~~~~
net.cpp:56:5: warning: 'last' may be used uninitialized in this function [-Wmaybe-uninitialized]
   56 |  if(last != leaf.size() - 1)
      |     ^~~~

Subtask #1
18.0 / 18.0

# Verdict Execution time Memory Grader output
1 Correct 8 ms 11980 KB Output is correct
2 Correct 8 ms 11980 KB Output is correct
3 Correct 8 ms 11980 KB Output is correct
4 Correct 8 ms 11980 KB Output is correct
5 Correct 8 ms 11980 KB Output is correct
6 Correct 8 ms 11980 KB Output is correct
7 Correct 8 ms 12056 KB Output is correct
8 Correct 8 ms 11980 KB Output is correct
9 Correct 8 ms 12052 KB Output is correct
10 Correct 8 ms 11980 KB Output is correct
11 Correct 9 ms 11980 KB Output is correct
12 Correct 8 ms 12028 KB Output is correct
13 Correct 8 ms 12052 KB Output is correct
14 Correct 8 ms 12024 KB Output is correct
15 Correct 8 ms 11980 KB Output is correct
16 Correct 8 ms 11980 KB Output is correct
17 Correct 8 ms 11992 KB Output is correct
18 Correct 8 ms 11980 KB Output is correct
19 Correct 8 ms 11980 KB Output is correct
20 Correct 8 ms 11980 KB Output is correct

Subtask #2
45.0 / 45.0

# Verdict Execution time Memory Grader output
1 Correct 8 ms 11980 KB Output is correct
2 Correct 8 ms 11980 KB Output is correct
3 Correct 8 ms 11980 KB Output is correct
4 Correct 8 ms 11980 KB Output is correct
5 Correct 8 ms 11980 KB Output is correct
6 Correct 8 ms 11980 KB Output is correct
7 Correct 8 ms 12056 KB Output is correct
8 Correct 8 ms 11980 KB Output is correct
9 Correct 8 ms 12052 KB Output is correct
10 Correct 8 ms 11980 KB Output is correct
11 Correct 9 ms 11980 KB Output is correct
12 Correct 8 ms 12028 KB Output is correct
13 Correct 8 ms 12052 KB Output is correct
14 Correct 8 ms 12024 KB Output is correct
15 Correct 8 ms 11980 KB Output is correct
16 Correct 8 ms 11980 KB Output is correct
17 Correct 8 ms 11992 KB Output is correct
18 Correct 8 ms 11980 KB Output is correct
19 Correct 8 ms 11980 KB Output is correct
20 Correct 8 ms 11980 KB Output is correct
21 Correct 8 ms 11980 KB Output is correct
22 Correct 10 ms 12108 KB Output is correct
23 Correct 10 ms 12108 KB Output is correct
24 Correct 10 ms 12108 KB Output is correct
25 Correct 9 ms 12108 KB Output is correct
26 Correct 8 ms 12124 KB Output is correct
27 Correct 9 ms 12108 KB Output is correct
28 Correct 10 ms 12088 KB Output is correct
29 Correct 8 ms 12108 KB Output is correct
30 Correct 8 ms 11980 KB Output is correct
31 Correct 9 ms 12144 KB Output is correct
32 Correct 8 ms 12020 KB Output is correct
33 Correct 8 ms 12052 KB Output is correct
34 Correct 9 ms 12016 KB Output is correct
35 Correct 8 ms 11980 KB Output is correct
36 Correct 8 ms 11976 KB Output is correct
37 Correct 8 ms 11980 KB Output is correct
38 Correct 8 ms 12108 KB Output is correct
39 Correct 8 ms 11980 KB Output is correct
40 Correct 8 ms 11980 KB Output is correct
41 Correct 8 ms 12056 KB Output is correct
42 Correct 8 ms 11980 KB Output is correct
43 Correct 8 ms 12112 KB Output is correct
44 Correct 9 ms 12036 KB Output is correct
45 Correct 9 ms 12064 KB Output is correct
46 Correct 8 ms 11980 KB Output is correct
47 Correct 8 ms 11980 KB Output is correct
48 Correct 9 ms 11980 KB Output is correct
49 Correct 8 ms 12108 KB Output is correct
50 Correct 8 ms 11980 KB Output is correct
51 Correct 8 ms 11988 KB Output is correct
52 Correct 8 ms 11996 KB Output is correct
53 Correct 9 ms 12108 KB Output is correct
54 Correct 8 ms 11980 KB Output is correct
55 Correct 9 ms 11980 KB Output is correct
56 Correct 8 ms 11980 KB Output is correct
57 Correct 8 ms 11980 KB Output is correct
58 Correct 9 ms 12092 KB Output is correct

Subtask #3
37.0 / 37.0

# Verdict Execution time Memory Grader output
1 Correct 8 ms 11980 KB Output is correct
2 Correct 8 ms 11980 KB Output is correct
3 Correct 8 ms 11980 KB Output is correct
4 Correct 8 ms 11980 KB Output is correct
5 Correct 8 ms 11980 KB Output is correct
6 Correct 8 ms 11980 KB Output is correct
7 Correct 8 ms 12056 KB Output is correct
8 Correct 8 ms 11980 KB Output is correct
9 Correct 8 ms 12052 KB Output is correct
10 Correct 8 ms 11980 KB Output is correct
11 Correct 9 ms 11980 KB Output is correct
12 Correct 8 ms 12028 KB Output is correct
13 Correct 8 ms 12052 KB Output is correct
14 Correct 8 ms 12024 KB Output is correct
15 Correct 8 ms 11980 KB Output is correct
16 Correct 8 ms 11980 KB Output is correct
17 Correct 8 ms 11992 KB Output is correct
18 Correct 8 ms 11980 KB Output is correct
19 Correct 8 ms 11980 KB Output is correct
20 Correct 8 ms 11980 KB Output is correct
21 Correct 8 ms 11980 KB Output is correct
22 Correct 10 ms 12108 KB Output is correct
23 Correct 10 ms 12108 KB Output is correct
24 Correct 10 ms 12108 KB Output is correct
25 Correct 9 ms 12108 KB Output is correct
26 Correct 8 ms 12124 KB Output is correct
27 Correct 9 ms 12108 KB Output is correct
28 Correct 10 ms 12088 KB Output is correct
29 Correct 8 ms 12108 KB Output is correct
30 Correct 8 ms 11980 KB Output is correct
31 Correct 9 ms 12144 KB Output is correct
32 Correct 8 ms 12020 KB Output is correct
33 Correct 8 ms 12052 KB Output is correct
34 Correct 9 ms 12016 KB Output is correct
35 Correct 8 ms 11980 KB Output is correct
36 Correct 8 ms 11976 KB Output is correct
37 Correct 8 ms 11980 KB Output is correct
38 Correct 8 ms 12108 KB Output is correct
39 Correct 8 ms 11980 KB Output is correct
40 Correct 8 ms 11980 KB Output is correct
41 Correct 8 ms 12056 KB Output is correct
42 Correct 8 ms 11980 KB Output is correct
43 Correct 8 ms 12112 KB Output is correct
44 Correct 9 ms 12036 KB Output is correct
45 Correct 9 ms 12064 KB Output is correct
46 Correct 8 ms 11980 KB Output is correct
47 Correct 8 ms 11980 KB Output is correct
48 Correct 9 ms 11980 KB Output is correct
49 Correct 8 ms 12108 KB Output is correct
50 Correct 8 ms 11980 KB Output is correct
51 Correct 8 ms 11988 KB Output is correct
52 Correct 8 ms 11996 KB Output is correct
53 Correct 9 ms 12108 KB Output is correct
54 Correct 8 ms 11980 KB Output is correct
55 Correct 9 ms 11980 KB Output is correct
56 Correct 8 ms 11980 KB Output is correct
57 Correct 8 ms 11980 KB Output is correct
58 Correct 9 ms 12092 KB Output is correct
59 Correct 369 ms 30016 KB Output is correct
60 Correct 435 ms 32048 KB Output is correct
61 Correct 8 ms 11980 KB Output is correct
62 Correct 8 ms 11980 KB Output is correct
63 Correct 322 ms 28308 KB Output is correct
64 Correct 11 ms 12492 KB Output is correct
65 Correct 23 ms 13956 KB Output is correct
66 Correct 156 ms 28204 KB Output is correct
67 Correct 498 ms 44460 KB Output is correct
68 Correct 502 ms 45300 KB Output is correct
69 Correct 17 ms 12808 KB Output is correct
70 Correct 91 ms 19124 KB Output is correct
71 Correct 318 ms 35064 KB Output is correct
72 Correct 357 ms 34404 KB Output is correct
73 Correct 91 ms 17348 KB Output is correct
74 Correct 445 ms 31088 KB Output is correct
75 Correct 32 ms 14576 KB Output is correct
76 Correct 386 ms 34848 KB Output is correct
77 Correct 330 ms 35104 KB Output is correct
78 Correct 36 ms 15180 KB Output is correct
79 Correct 508 ms 42068 KB Output is correct
80 Correct 10 ms 12236 KB Output is correct
81 Correct 108 ms 19204 KB Output is correct
82 Correct 409 ms 33176 KB Output is correct
83 Correct 469 ms 31032 KB Output is correct
84 Correct 461 ms 31052 KB Output is correct
85 Correct 465 ms 31224 KB Output is correct
86 Correct 498 ms 32116 KB Output is correct
87 Correct 433 ms 32256 KB Output is correct