Submission #848225

#	Submission time	Handle	Problem	Language	Result	Execution time	Memory
848225	2023-09-11T17:18:34 Z	Hakiers	Network (BOI15_net)	C++17	63 / 100	608 ms	262144 KB

#include <bits/stdc++.h>
using namespace std;
const int MAXN = 5e5 + 7;
vector<int> G[MAXN];
int parent[MAXN];
pair<int, int> dp[MAXN];
tuple<int, int, int> vein;
vector<queue<int>> Q;
queue<int> sajz;
int n;

void dfsVein(int v, int p){

	if((int)G[v].size() == 1) dp[v].second = v;
	else dp[v].first = -1;
	
	int max1 = v;
	for(auto u : G[v]){
		if(u == p) continue;
		dfsVein(u, v);
		
		if(dp[u].first > dp[max1].first)
			max1 = u;
	}
	
	
	// albo merguje ui z uj lub ide w gore
	
	for(auto u : G[v])
		if(u != p && u != max1) vein = max(vein, make_tuple(dp[u].first + dp[max1].first + (int)G[v].size() - 2, dp[max1].second, dp[u].second));
		
	

	dp[v] = dp[max1];
	dp[v].first += max((int)G[v].size() - 2, 0);
}

void dfs(int v, int p){
	parent[v] = p;
	
	for(auto u : G[v])
		if(u != p) dfs(u, v);
	
}

void dfs_push(int v, int p){
	
	for(auto u : G[v])
		if(u != p) dfs_push(u, v);
	
	if((int)G[v].size() == 1) sajz.push(v);

}


void compute(int u, int v){
	
	while(u != v){
		
		for(auto w : G[parent[u]]){
			if(w == u || w == parent[parent[u]]) continue;
			sajz = std::queue<int>();
			dfs_push(w, parent[u]);
			Q.push_back(sajz);
		}
		
		u = parent[u];
	}

}

bool cmp(queue<int> &a, queue<int> &b){
	return (int)a.size() > (int)b.size();
}

int main(){
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	cin >> n;
	
	for(int i = 1; i < n; i++){
		int a, b;
		cin >> a >> b;
		G[a].push_back(b);
		G[b].push_back(a);
	}
	
	dfsVein(1, 1);
	auto [val, u1, u2] = vein;
	dfs(u1, u1);
	
	compute(u2, u1);
	sort(Q.begin(), Q.end(), cmp);
	/*
	cout << " val: " << val << " u1: " << u1 << " u2:" << u2 << endl;
	
	for(auto x : Q){
		while(x.size()){
			cout << (int)x.front() << " ";
			x.pop();
		}
		cout << endl;
	}
	*/
	
	vector<pair<int, int>> anserw;
	anserw.push_back({u1, u2});
	
	sajz = std::queue<int>(); // clearunemy sajza
	
	
	for(auto x : Q){
		while(x.size() && sajz.size()){
			anserw.push_back({x.front(), sajz.front()});
			x.pop();
			sajz.pop();
		}
		
		while(x.size()){
			sajz.push(x.front());
			x.pop();
		}
	}
	
	while(sajz.size()){
		anserw.push_back({u1, sajz.front()});
		sajz.pop();
	}
	
	cout << anserw.size() << "\n";
	for(auto [x, y] : anserw)
		cout << x << " " << y << "\n";
	
	
	
}


/*

27
1 2
2 3
3 4
4 5
5 6
6 7
7 8
8 9
8 10
8 11
8 12
5 13
13 14
14 15
14 16
14 17
14 18
8 19
4 20
20 21
21 22
21 23
21 24
21 25
21 26
2 27
*/

Subtask #1
18.0 / 18.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	3 ms	15708 KB	Output is correct
2	Correct	3 ms	15860 KB	Output is correct
3	Correct	4 ms	15708 KB	Output is correct
4	Correct	3 ms	15704 KB	Output is correct
5	Correct	3 ms	15708 KB	Output is correct
6	Correct	4 ms	15708 KB	Output is correct
7	Correct	3 ms	15708 KB	Output is correct
8	Correct	3 ms	15708 KB	Output is correct
9	Correct	3 ms	15708 KB	Output is correct
10	Correct	3 ms	15708 KB	Output is correct
11	Correct	3 ms	15704 KB	Output is correct
12	Correct	3 ms	15708 KB	Output is correct
13	Correct	3 ms	15708 KB	Output is correct
14	Correct	3 ms	15708 KB	Output is correct
15	Correct	3 ms	15708 KB	Output is correct
16	Correct	3 ms	15704 KB	Output is correct
17	Correct	3 ms	15708 KB	Output is correct
18	Correct	3 ms	15708 KB	Output is correct
19	Correct	3 ms	15708 KB	Output is correct
20	Correct	4 ms	15704 KB	Output is correct

Subtask #2
45.0 / 45.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	3 ms	15708 KB	Output is correct
2	Correct	3 ms	15860 KB	Output is correct
3	Correct	4 ms	15708 KB	Output is correct
4	Correct	3 ms	15704 KB	Output is correct
5	Correct	3 ms	15708 KB	Output is correct
6	Correct	4 ms	15708 KB	Output is correct
7	Correct	3 ms	15708 KB	Output is correct
8	Correct	3 ms	15708 KB	Output is correct
9	Correct	3 ms	15708 KB	Output is correct
10	Correct	3 ms	15708 KB	Output is correct
11	Correct	3 ms	15704 KB	Output is correct
12	Correct	3 ms	15708 KB	Output is correct
13	Correct	3 ms	15708 KB	Output is correct
14	Correct	3 ms	15708 KB	Output is correct
15	Correct	3 ms	15708 KB	Output is correct
16	Correct	3 ms	15704 KB	Output is correct
17	Correct	3 ms	15708 KB	Output is correct
18	Correct	3 ms	15708 KB	Output is correct
19	Correct	3 ms	15708 KB	Output is correct
20	Correct	4 ms	15704 KB	Output is correct
21	Correct	3 ms	15704 KB	Output is correct
22	Correct	5 ms	17240 KB	Output is correct
23	Correct	5 ms	17244 KB	Output is correct
24	Correct	5 ms	17244 KB	Output is correct
25	Correct	4 ms	16476 KB	Output is correct
26	Correct	4 ms	16476 KB	Output is correct
27	Correct	5 ms	15964 KB	Output is correct
28	Correct	4 ms	15964 KB	Output is correct
29	Correct	4 ms	15964 KB	Output is correct
30	Correct	3 ms	15708 KB	Output is correct
31	Correct	4 ms	15964 KB	Output is correct
32	Correct	3 ms	15708 KB	Output is correct
33	Correct	3 ms	15704 KB	Output is correct
34	Correct	3 ms	15708 KB	Output is correct
35	Correct	3 ms	15708 KB	Output is correct
36	Correct	3 ms	15704 KB	Output is correct
37	Correct	3 ms	15708 KB	Output is correct
38	Correct	3 ms	15960 KB	Output is correct
39	Correct	4 ms	15960 KB	Output is correct
40	Correct	5 ms	15704 KB	Output is correct
41	Correct	3 ms	15704 KB	Output is correct
42	Correct	4 ms	16220 KB	Output is correct
43	Correct	5 ms	16476 KB	Output is correct
44	Correct	3 ms	15704 KB	Output is correct
45	Correct	3 ms	15708 KB	Output is correct
46	Correct	3 ms	15964 KB	Output is correct
47	Correct	3 ms	15708 KB	Output is correct
48	Correct	3 ms	15964 KB	Output is correct
49	Correct	4 ms	16476 KB	Output is correct
50	Correct	3 ms	15876 KB	Output is correct
51	Correct	3 ms	15708 KB	Output is correct
52	Correct	3 ms	15960 KB	Output is correct
53	Correct	4 ms	16112 KB	Output is correct
54	Correct	3 ms	15708 KB	Output is correct
55	Correct	3 ms	15964 KB	Output is correct
56	Correct	4 ms	15708 KB	Output is correct
57	Correct	4 ms	16220 KB	Output is correct
58	Correct	5 ms	17140 KB	Output is correct

Subtask #3
0 / 37.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	3 ms	15708 KB	Output is correct
2	Correct	3 ms	15860 KB	Output is correct
3	Correct	4 ms	15708 KB	Output is correct
4	Correct	3 ms	15704 KB	Output is correct
5	Correct	3 ms	15708 KB	Output is correct
6	Correct	4 ms	15708 KB	Output is correct
7	Correct	3 ms	15708 KB	Output is correct
8	Correct	3 ms	15708 KB	Output is correct
9	Correct	3 ms	15708 KB	Output is correct
10	Correct	3 ms	15708 KB	Output is correct
11	Correct	3 ms	15704 KB	Output is correct
12	Correct	3 ms	15708 KB	Output is correct
13	Correct	3 ms	15708 KB	Output is correct
14	Correct	3 ms	15708 KB	Output is correct
15	Correct	3 ms	15708 KB	Output is correct
16	Correct	3 ms	15704 KB	Output is correct
17	Correct	3 ms	15708 KB	Output is correct
18	Correct	3 ms	15708 KB	Output is correct
19	Correct	3 ms	15708 KB	Output is correct
20	Correct	4 ms	15704 KB	Output is correct
21	Correct	3 ms	15704 KB	Output is correct
22	Correct	5 ms	17240 KB	Output is correct
23	Correct	5 ms	17244 KB	Output is correct
24	Correct	5 ms	17244 KB	Output is correct
25	Correct	4 ms	16476 KB	Output is correct
26	Correct	4 ms	16476 KB	Output is correct
27	Correct	5 ms	15964 KB	Output is correct
28	Correct	4 ms	15964 KB	Output is correct
29	Correct	4 ms	15964 KB	Output is correct
30	Correct	3 ms	15708 KB	Output is correct
31	Correct	4 ms	15964 KB	Output is correct
32	Correct	3 ms	15708 KB	Output is correct
33	Correct	3 ms	15704 KB	Output is correct
34	Correct	3 ms	15708 KB	Output is correct
35	Correct	3 ms	15708 KB	Output is correct
36	Correct	3 ms	15704 KB	Output is correct
37	Correct	3 ms	15708 KB	Output is correct
38	Correct	3 ms	15960 KB	Output is correct
39	Correct	4 ms	15960 KB	Output is correct
40	Correct	5 ms	15704 KB	Output is correct
41	Correct	3 ms	15704 KB	Output is correct
42	Correct	4 ms	16220 KB	Output is correct
43	Correct	5 ms	16476 KB	Output is correct
44	Correct	3 ms	15704 KB	Output is correct
45	Correct	3 ms	15708 KB	Output is correct
46	Correct	3 ms	15964 KB	Output is correct
47	Correct	3 ms	15708 KB	Output is correct
48	Correct	3 ms	15964 KB	Output is correct
49	Correct	4 ms	16476 KB	Output is correct
50	Correct	3 ms	15876 KB	Output is correct
51	Correct	3 ms	15708 KB	Output is correct
52	Correct	3 ms	15960 KB	Output is correct
53	Correct	4 ms	16112 KB	Output is correct
54	Correct	3 ms	15708 KB	Output is correct
55	Correct	3 ms	15964 KB	Output is correct
56	Correct	4 ms	15708 KB	Output is correct
57	Correct	4 ms	16220 KB	Output is correct
58	Correct	5 ms	17140 KB	Output is correct
59	Correct	530 ms	210740 KB	Output is correct
60	Correct	402 ms	40828 KB	Output is correct
61	Correct	3 ms	15704 KB	Output is correct
62	Correct	3 ms	15708 KB	Output is correct
63	Correct	402 ms	122520 KB	Output is correct
64	Correct	5 ms	16472 KB	Output is correct
65	Correct	13 ms	21700 KB	Output is correct
66	Correct	99 ms	44948 KB	Output is correct
67	Correct	480 ms	67044 KB	Output is correct
68	Correct	608 ms	112088 KB	Output is correct
69	Correct	23 ms	27504 KB	Output is correct
70	Correct	266 ms	200280 KB	Output is correct
71	Runtime error	364 ms	262144 KB	Execution killed with signal 9
72	Halted	0 ms	0 KB	-

Submission #848225

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