Submission #480594

#	Submission time	Handle	Problem	Language	Result	Execution time	Memory
480594	2021-10-17T08:15:19 Z	Sohsoh84	Network (BOI15_net)	C++17	100 / 100	494 ms	61484 KB

//: // ////: ///  / : //// / :
#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair<int, int> pll;

#define all(x)			(x).begin(),(x).end()
#define X			first
#define Y			second
#define sep			' '
#define endl			'\n'
#define debug(x)		cerr << #x << ": " <<  x << endl;

const ll MAXN = 1e6 + 10;

int n, tin[MAXN], t;
vector<int> adj[MAXN], L;
vector<pll> ans;

void dfs(int v, int p) {
	tin[v] = ++t;
	if (adj[v].size() == 1)
		L.push_back(v);

	for (int u : adj[v])
		if (u != p)
			dfs(u, v);
}

int main() {
	ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
	int n;
	cin >> n;
	for (int i = 1; i < n; i++) {
		int u, v;
		cin >> u >> v;
		adj[u].push_back(v);
		adj[v].push_back(u);
	}

	for (int i = 1; i <= n; i++) {
		if (adj[i].size() > 1) {
			dfs(i, 0);
			break;
		}
	}

	sort(all(L), [] (int a, int b) {
		return tin[a] < tin[b];	
	});

	for (int i = 0; i < L.size() / 2; i++)
		ans.push_back({L[i], L[i + L.size() / 2]});

	if (L.size() & 1) ans.push_back({L.back(), L.front()});
	
	cout << ans.size() << endl;
	for (pll e : ans) cout << e.X << sep << e.Y << endl;
	return 0;
}

Compilation message

net.cpp: In function 'int main()':
net.cpp:54:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   54 |  for (int i = 0; i < L.size() / 2; i++)
      |                  ~~^~~~~~~~~~~~~~

Subtask #1
18.0 / 18.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	13 ms	23756 KB	Output is correct
2	Correct	12 ms	23800 KB	Output is correct
3	Correct	12 ms	23764 KB	Output is correct
4	Correct	12 ms	23808 KB	Output is correct
5	Correct	14 ms	23800 KB	Output is correct
6	Correct	12 ms	23756 KB	Output is correct
7	Correct	14 ms	23716 KB	Output is correct
8	Correct	13 ms	23736 KB	Output is correct
9	Correct	14 ms	23756 KB	Output is correct
10	Correct	14 ms	23808 KB	Output is correct
11	Correct	13 ms	23756 KB	Output is correct
12	Correct	14 ms	23756 KB	Output is correct
13	Correct	14 ms	23756 KB	Output is correct
14	Correct	13 ms	23756 KB	Output is correct
15	Correct	13 ms	23756 KB	Output is correct
16	Correct	15 ms	23780 KB	Output is correct
17	Correct	15 ms	23756 KB	Output is correct
18	Correct	14 ms	23756 KB	Output is correct
19	Correct	15 ms	23808 KB	Output is correct
20	Correct	15 ms	23892 KB	Output is correct

Subtask #2
45.0 / 45.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	13 ms	23756 KB	Output is correct
2	Correct	12 ms	23800 KB	Output is correct
3	Correct	12 ms	23764 KB	Output is correct
4	Correct	12 ms	23808 KB	Output is correct
5	Correct	14 ms	23800 KB	Output is correct
6	Correct	12 ms	23756 KB	Output is correct
7	Correct	14 ms	23716 KB	Output is correct
8	Correct	13 ms	23736 KB	Output is correct
9	Correct	14 ms	23756 KB	Output is correct
10	Correct	14 ms	23808 KB	Output is correct
11	Correct	13 ms	23756 KB	Output is correct
12	Correct	14 ms	23756 KB	Output is correct
13	Correct	14 ms	23756 KB	Output is correct
14	Correct	13 ms	23756 KB	Output is correct
15	Correct	13 ms	23756 KB	Output is correct
16	Correct	15 ms	23780 KB	Output is correct
17	Correct	15 ms	23756 KB	Output is correct
18	Correct	14 ms	23756 KB	Output is correct
19	Correct	15 ms	23808 KB	Output is correct
20	Correct	15 ms	23892 KB	Output is correct
21	Correct	16 ms	23756 KB	Output is correct
22	Correct	18 ms	23924 KB	Output is correct
23	Correct	15 ms	23884 KB	Output is correct
24	Correct	15 ms	23980 KB	Output is correct
25	Correct	15 ms	23884 KB	Output is correct
26	Correct	14 ms	23884 KB	Output is correct
27	Correct	15 ms	23884 KB	Output is correct
28	Correct	15 ms	23848 KB	Output is correct
29	Correct	15 ms	23856 KB	Output is correct
30	Correct	15 ms	23808 KB	Output is correct
31	Correct	16 ms	23884 KB	Output is correct
32	Correct	13 ms	23756 KB	Output is correct
33	Correct	16 ms	23760 KB	Output is correct
34	Correct	15 ms	23756 KB	Output is correct
35	Correct	13 ms	23804 KB	Output is correct
36	Correct	14 ms	23776 KB	Output is correct
37	Correct	13 ms	23724 KB	Output is correct
38	Correct	13 ms	23756 KB	Output is correct
39	Correct	13 ms	23800 KB	Output is correct
40	Correct	17 ms	23756 KB	Output is correct
41	Correct	17 ms	23756 KB	Output is correct
42	Correct	15 ms	23756 KB	Output is correct
43	Correct	16 ms	23812 KB	Output is correct
44	Correct	13 ms	23756 KB	Output is correct
45	Correct	14 ms	23808 KB	Output is correct
46	Correct	14 ms	23756 KB	Output is correct
47	Correct	13 ms	23768 KB	Output is correct
48	Correct	13 ms	23800 KB	Output is correct
49	Correct	15 ms	23852 KB	Output is correct
50	Correct	16 ms	23804 KB	Output is correct
51	Correct	13 ms	23756 KB	Output is correct
52	Correct	13 ms	23756 KB	Output is correct
53	Correct	14 ms	23756 KB	Output is correct
54	Correct	14 ms	23804 KB	Output is correct
55	Correct	14 ms	23860 KB	Output is correct
56	Correct	13 ms	23800 KB	Output is correct
57	Correct	15 ms	23728 KB	Output is correct
58	Correct	16 ms	23944 KB	Output is correct

Subtask #3
37.0 / 37.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	13 ms	23756 KB	Output is correct
2	Correct	12 ms	23800 KB	Output is correct
3	Correct	12 ms	23764 KB	Output is correct
4	Correct	12 ms	23808 KB	Output is correct
5	Correct	14 ms	23800 KB	Output is correct
6	Correct	12 ms	23756 KB	Output is correct
7	Correct	14 ms	23716 KB	Output is correct
8	Correct	13 ms	23736 KB	Output is correct
9	Correct	14 ms	23756 KB	Output is correct
10	Correct	14 ms	23808 KB	Output is correct
11	Correct	13 ms	23756 KB	Output is correct
12	Correct	14 ms	23756 KB	Output is correct
13	Correct	14 ms	23756 KB	Output is correct
14	Correct	13 ms	23756 KB	Output is correct
15	Correct	13 ms	23756 KB	Output is correct
16	Correct	15 ms	23780 KB	Output is correct
17	Correct	15 ms	23756 KB	Output is correct
18	Correct	14 ms	23756 KB	Output is correct
19	Correct	15 ms	23808 KB	Output is correct
20	Correct	15 ms	23892 KB	Output is correct
21	Correct	16 ms	23756 KB	Output is correct
22	Correct	18 ms	23924 KB	Output is correct
23	Correct	15 ms	23884 KB	Output is correct
24	Correct	15 ms	23980 KB	Output is correct
25	Correct	15 ms	23884 KB	Output is correct
26	Correct	14 ms	23884 KB	Output is correct
27	Correct	15 ms	23884 KB	Output is correct
28	Correct	15 ms	23848 KB	Output is correct
29	Correct	15 ms	23856 KB	Output is correct
30	Correct	15 ms	23808 KB	Output is correct
31	Correct	16 ms	23884 KB	Output is correct
32	Correct	13 ms	23756 KB	Output is correct
33	Correct	16 ms	23760 KB	Output is correct
34	Correct	15 ms	23756 KB	Output is correct
35	Correct	13 ms	23804 KB	Output is correct
36	Correct	14 ms	23776 KB	Output is correct
37	Correct	13 ms	23724 KB	Output is correct
38	Correct	13 ms	23756 KB	Output is correct
39	Correct	13 ms	23800 KB	Output is correct
40	Correct	17 ms	23756 KB	Output is correct
41	Correct	17 ms	23756 KB	Output is correct
42	Correct	15 ms	23756 KB	Output is correct
43	Correct	16 ms	23812 KB	Output is correct
44	Correct	13 ms	23756 KB	Output is correct
45	Correct	14 ms	23808 KB	Output is correct
46	Correct	14 ms	23756 KB	Output is correct
47	Correct	13 ms	23768 KB	Output is correct
48	Correct	13 ms	23800 KB	Output is correct
49	Correct	15 ms	23852 KB	Output is correct
50	Correct	16 ms	23804 KB	Output is correct
51	Correct	13 ms	23756 KB	Output is correct
52	Correct	13 ms	23756 KB	Output is correct
53	Correct	14 ms	23756 KB	Output is correct
54	Correct	14 ms	23804 KB	Output is correct
55	Correct	14 ms	23860 KB	Output is correct
56	Correct	13 ms	23800 KB	Output is correct
57	Correct	15 ms	23728 KB	Output is correct
58	Correct	16 ms	23944 KB	Output is correct
59	Correct	366 ms	50648 KB	Output is correct
60	Correct	442 ms	53664 KB	Output is correct
61	Correct	14 ms	23756 KB	Output is correct
62	Correct	12 ms	23756 KB	Output is correct
63	Correct	323 ms	47976 KB	Output is correct
64	Correct	15 ms	24140 KB	Output is correct
65	Correct	24 ms	25788 KB	Output is correct
66	Correct	138 ms	40260 KB	Output is correct
67	Correct	460 ms	60600 KB	Output is correct
68	Correct	494 ms	61484 KB	Output is correct
69	Correct	18 ms	24780 KB	Output is correct
70	Correct	126 ms	34092 KB	Output is correct
71	Correct	339 ms	57548 KB	Output is correct
72	Correct	342 ms	56108 KB	Output is correct
73	Correct	95 ms	31560 KB	Output is correct
74	Correct	480 ms	52388 KB	Output is correct
75	Correct	36 ms	27440 KB	Output is correct
76	Correct	313 ms	57136 KB	Output is correct
77	Correct	308 ms	57208 KB	Output is correct
78	Correct	40 ms	27460 KB	Output is correct
79	Correct	449 ms	58752 KB	Output is correct
80	Correct	14 ms	24012 KB	Output is correct
81	Correct	112 ms	34152 KB	Output is correct
82	Correct	421 ms	54620 KB	Output is correct
83	Correct	455 ms	52352 KB	Output is correct
84	Correct	446 ms	52264 KB	Output is correct
85	Correct	420 ms	52268 KB	Output is correct
86	Correct	423 ms	53764 KB	Output is correct
87	Correct	431 ms	53808 KB	Output is correct

Submission #480594

Compilation message

Subtask #1 18.0 / 18.0

Subtask #2 45.0 / 45.0

Subtask #3 37.0 / 37.0

Subtask #1
18.0 / 18.0

Subtask #2
45.0 / 45.0

Subtask #3
37.0 / 37.0