Submission #605838

#	Submission time	Handle	Problem	Language	Result	Execution time	Memory
605838	2022-07-26T03:22:16 Z	buidangnguyen05	Network (BOI15_net)	C++14	63 / 100	1982 ms	86856 KB

//source: https://oj.uz/problem/view/BOI15_net
 
#include<bits/stdc++.h>
using namespace std;
 
typedef long long ll;
 
const int N = 5e5 + 10;
vector<int> adj[N]; 
vector<pair<int, int>> ans;
 
vector<int> dfs(int x, int par) {
	if (adj[x].size() == 1) return vector<int>(1, x);
	vector<int> cur; 
	for (int i : adj[x]) if (i != par) {
		vector<int> v = dfs(i, x);
		if (cur.size() < v.size()) swap(v, cur);
		while (cur.size() + v.size() > 2 && v.size()) {
			int p = cur.back(); cur.pop_back();
			int q = v.back(); v.pop_back();
			cerr << x << " " << p << " " << q << "\n";
			ans.emplace_back(p, q);
		}
		for (int j : v) cur.push_back(j);
	}
	return cur;
}
 
signed main() {
	cin.tie(0)->sync_with_stdio(0);
	if (fopen("task.inp", "r")) {
		freopen("task.inp", "r", stdin);
		freopen("task.out", "w", stdout);
	}
	
	int n; cin >> n;
	for (int i = 1; i < n; ++i) {
		int x, y; cin >> x >> y;
		adj[x].push_back(y); adj[y].push_back(x);
		//ans.emplace_back(x, y);
	}
 
	int root = 0, save1 = 0, save2 = 0;
	for (int i = 1; i <= n; ++i) {
		if (adj[i].size() > 1 && !root) root = i;
		else if (adj[i].size() == 1 && !save1) save1 = i;
		else if (adj[i].size() == 1 && !save2) save2 = i;
	}
	//cerr << root << "\n";
	vector<int> rem = dfs(root, 0);
	if (rem.size() > 1) {
		int u = rem.back(); rem.pop_back();
		int v = rem.back(); rem.pop_back();
		ans.emplace_back(u, v);
	}
	if (rem.size()) ans.emplace_back(rem.back(), (save1 == rem.back() ? save2 : save1));
	cout << ans.size() << "\n";
	for (pair<int, int> i : ans) cout << i.first << " " << i.second << "\n";
	cout << endl;
	//system("graph_.exe");
}

Compilation message

net.cpp: In function 'int main()':
net.cpp:32:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   32 |   freopen("task.inp", "r", stdin);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
net.cpp:33:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   33 |   freopen("task.out", "w", stdout);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

Subtask #1
18.0 / 18.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	6 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	7 ms	11988 KB	Output is correct
5	Correct	6 ms	11988 KB	Output is correct
6	Correct	7 ms	12044 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	11988 KB	Output is correct
10	Correct	8 ms	11988 KB	Output is correct
11	Correct	6 ms	11988 KB	Output is correct
12	Correct	6 ms	11988 KB	Output is correct
13	Correct	6 ms	11988 KB	Output is correct
14	Correct	6 ms	11988 KB	Output is correct
15	Correct	6 ms	11988 KB	Output is correct
16	Correct	6 ms	11988 KB	Output is correct
17	Correct	6 ms	11988 KB	Output is correct
18	Correct	6 ms	11988 KB	Output is correct
19	Correct	6 ms	11988 KB	Output is correct
20	Correct	5 ms	11988 KB	Output is correct

Subtask #2
45.0 / 45.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	6 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	7 ms	11988 KB	Output is correct
5	Correct	6 ms	11988 KB	Output is correct
6	Correct	7 ms	12044 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	11988 KB	Output is correct
10	Correct	8 ms	11988 KB	Output is correct
11	Correct	6 ms	11988 KB	Output is correct
12	Correct	6 ms	11988 KB	Output is correct
13	Correct	6 ms	11988 KB	Output is correct
14	Correct	6 ms	11988 KB	Output is correct
15	Correct	6 ms	11988 KB	Output is correct
16	Correct	6 ms	11988 KB	Output is correct
17	Correct	6 ms	11988 KB	Output is correct
18	Correct	6 ms	11988 KB	Output is correct
19	Correct	6 ms	11988 KB	Output is correct
20	Correct	5 ms	11988 KB	Output is correct
21	Correct	6 ms	11988 KB	Output is correct
22	Correct	16 ms	12152 KB	Output is correct
23	Correct	16 ms	12176 KB	Output is correct
24	Correct	15 ms	12116 KB	Output is correct
25	Correct	11 ms	12156 KB	Output is correct
26	Correct	10 ms	12144 KB	Output is correct
27	Correct	12 ms	12136 KB	Output is correct
28	Correct	11 ms	12044 KB	Output is correct
29	Correct	10 ms	12116 KB	Output is correct
30	Correct	6 ms	11988 KB	Output is correct
31	Correct	11 ms	12116 KB	Output is correct
32	Correct	6 ms	11988 KB	Output is correct
33	Correct	6 ms	11988 KB	Output is correct
34	Correct	6 ms	12060 KB	Output is correct
35	Correct	6 ms	11988 KB	Output is correct
36	Correct	7 ms	11988 KB	Output is correct
37	Correct	8 ms	12068 KB	Output is correct
38	Correct	8 ms	12244 KB	Output is correct
39	Correct	7 ms	11988 KB	Output is correct
40	Correct	7 ms	12064 KB	Output is correct
41	Correct	6 ms	12068 KB	Output is correct
42	Correct	8 ms	11988 KB	Output is correct
43	Correct	11 ms	12072 KB	Output is correct
44	Correct	7 ms	11988 KB	Output is correct
45	Correct	7 ms	11980 KB	Output is correct
46	Correct	10 ms	11988 KB	Output is correct
47	Correct	7 ms	11988 KB	Output is correct
48	Correct	7 ms	12064 KB	Output is correct
49	Correct	11 ms	12076 KB	Output is correct
50	Correct	7 ms	12060 KB	Output is correct
51	Correct	6 ms	11988 KB	Output is correct
52	Correct	6 ms	12116 KB	Output is correct
53	Correct	7 ms	12116 KB	Output is correct
54	Correct	6 ms	11988 KB	Output is correct
55	Correct	7 ms	11988 KB	Output is correct
56	Correct	6 ms	12064 KB	Output is correct
57	Correct	9 ms	11988 KB	Output is correct
58	Correct	15 ms	12168 KB	Output is correct

Subtask #3
0 / 37.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	6 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	7 ms	11988 KB	Output is correct
5	Correct	6 ms	11988 KB	Output is correct
6	Correct	7 ms	12044 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	11988 KB	Output is correct
10	Correct	8 ms	11988 KB	Output is correct
11	Correct	6 ms	11988 KB	Output is correct
12	Correct	6 ms	11988 KB	Output is correct
13	Correct	6 ms	11988 KB	Output is correct
14	Correct	6 ms	11988 KB	Output is correct
15	Correct	6 ms	11988 KB	Output is correct
16	Correct	6 ms	11988 KB	Output is correct
17	Correct	6 ms	11988 KB	Output is correct
18	Correct	6 ms	11988 KB	Output is correct
19	Correct	6 ms	11988 KB	Output is correct
20	Correct	5 ms	11988 KB	Output is correct
21	Correct	6 ms	11988 KB	Output is correct
22	Correct	16 ms	12152 KB	Output is correct
23	Correct	16 ms	12176 KB	Output is correct
24	Correct	15 ms	12116 KB	Output is correct
25	Correct	11 ms	12156 KB	Output is correct
26	Correct	10 ms	12144 KB	Output is correct
27	Correct	12 ms	12136 KB	Output is correct
28	Correct	11 ms	12044 KB	Output is correct
29	Correct	10 ms	12116 KB	Output is correct
30	Correct	6 ms	11988 KB	Output is correct
31	Correct	11 ms	12116 KB	Output is correct
32	Correct	6 ms	11988 KB	Output is correct
33	Correct	6 ms	11988 KB	Output is correct
34	Correct	6 ms	12060 KB	Output is correct
35	Correct	6 ms	11988 KB	Output is correct
36	Correct	7 ms	11988 KB	Output is correct
37	Correct	8 ms	12068 KB	Output is correct
38	Correct	8 ms	12244 KB	Output is correct
39	Correct	7 ms	11988 KB	Output is correct
40	Correct	7 ms	12064 KB	Output is correct
41	Correct	6 ms	12068 KB	Output is correct
42	Correct	8 ms	11988 KB	Output is correct
43	Correct	11 ms	12072 KB	Output is correct
44	Correct	7 ms	11988 KB	Output is correct
45	Correct	7 ms	11980 KB	Output is correct
46	Correct	10 ms	11988 KB	Output is correct
47	Correct	7 ms	11988 KB	Output is correct
48	Correct	7 ms	12064 KB	Output is correct
49	Correct	11 ms	12076 KB	Output is correct
50	Correct	7 ms	12060 KB	Output is correct
51	Correct	6 ms	11988 KB	Output is correct
52	Correct	6 ms	12116 KB	Output is correct
53	Correct	7 ms	12116 KB	Output is correct
54	Correct	6 ms	11988 KB	Output is correct
55	Correct	7 ms	11988 KB	Output is correct
56	Correct	6 ms	12064 KB	Output is correct
57	Correct	9 ms	11988 KB	Output is correct
58	Correct	15 ms	12168 KB	Output is correct
59	Correct	1347 ms	39276 KB	Output is correct
60	Correct	1588 ms	42180 KB	Output is correct
61	Correct	7 ms	11988 KB	Output is correct
62	Correct	6 ms	11988 KB	Output is correct
63	Correct	1313 ms	36620 KB	Output is correct
64	Correct	8 ms	13096 KB	Output is correct
65	Correct	21 ms	16516 KB	Output is correct
66	Correct	120 ms	51848 KB	Output is correct
67	Correct	431 ms	84588 KB	Output is correct
68	Correct	564 ms	86856 KB	Output is correct
69	Correct	63 ms	13000 KB	Output is correct
70	Correct	595 ms	22736 KB	Output is correct
71	Correct	1970 ms	47096 KB	Output is correct
72	Correct	1860 ms	45208 KB	Output is correct
73	Correct	317 ms	19760 KB	Output is correct
74	Correct	1283 ms	40460 KB	Output is correct
75	Correct	229 ms	15724 KB	Output is correct
76	Correct	1958 ms	46580 KB	Output is correct
77	Correct	1982 ms	46592 KB	Output is correct
78	Incorrect	79 ms	18488 KB	Breaking single line is causing network to disconnect.
79	Halted	0 ms	0 KB	-

Submission #605838

Compilation message

Subtask #1 18.0 / 18.0

Subtask #2 45.0 / 45.0

Subtask #3 0 / 37.0

Subtask #1
18.0 / 18.0

Subtask #2
45.0 / 45.0

Subtask #3
0 / 37.0