Submission #848230

#	Submission time	Handle	Problem	Language	Result	Execution time	Memory
848230	2023-09-11T17:39:24 Z	Hakiers	Network (BOI15_net)	C++17	100 / 100	544 ms	77084 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<vector<int>> Q;
vector<int> xd;
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) xd.push_back(v);

}


void compute(int u, int v){
	while(u != v){
		
		for(auto w : G[parent[u]]){
			if(w == u || w == parent[parent[u]]) continue;
			xd.clear();
			xd.shrink_to_fit();
			dfs_push(w, parent[u]);
			Q.push_back(xd);
		}
		
		u = parent[u];
	}

}

bool cmp(vector<int> &a, vector<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});
	
	queue<int> sajz;
	
	
	for(auto x : Q){
		int it = 0;
		
		for(; it < (int)x.size() && sajz.size(); it++){
			anserw.push_back({x[it], sajz.front()});
			sajz.pop();
		}
		
		for(; it < (int)x.size(); it++)
			sajz.push(x[it]);
		/*
		while(Q[x].size() && sajz.size()){
			anserw.push_back({Q[x].front(), sajz.front()});
			Q[x].pop();
			sajz.pop();
		}
		
		while(Q[x].size()){
			sajz.push(Q[x].front());
			Q[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	4 ms	16008 KB	Output is correct
2	Correct	4 ms	15708 KB	Output is correct
3	Correct	3 ms	15708 KB	Output is correct
4	Correct	3 ms	15708 KB	Output is correct
5	Correct	4 ms	15704 KB	Output is correct
6	Correct	3 ms	15708 KB	Output is correct
7	Correct	3 ms	15708 KB	Output is correct
8	Correct	4 ms	15708 KB	Output is correct
9	Correct	4 ms	15816 KB	Output is correct
10	Correct	4 ms	15708 KB	Output is correct
11	Correct	3 ms	15708 KB	Output is correct
12	Correct	3 ms	15708 KB	Output is correct
13	Correct	3 ms	15852 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	15708 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	3 ms	15708 KB	Output is correct

Subtask #2
45.0 / 45.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	4 ms	16008 KB	Output is correct
2	Correct	4 ms	15708 KB	Output is correct
3	Correct	3 ms	15708 KB	Output is correct
4	Correct	3 ms	15708 KB	Output is correct
5	Correct	4 ms	15704 KB	Output is correct
6	Correct	3 ms	15708 KB	Output is correct
7	Correct	3 ms	15708 KB	Output is correct
8	Correct	4 ms	15708 KB	Output is correct
9	Correct	4 ms	15816 KB	Output is correct
10	Correct	4 ms	15708 KB	Output is correct
11	Correct	3 ms	15708 KB	Output is correct
12	Correct	3 ms	15708 KB	Output is correct
13	Correct	3 ms	15852 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	15708 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	3 ms	15708 KB	Output is correct
21	Correct	3 ms	15964 KB	Output is correct
22	Correct	4 ms	15964 KB	Output is correct
23	Correct	4 ms	15964 KB	Output is correct
24	Correct	4 ms	15964 KB	Output is correct
25	Correct	4 ms	15964 KB	Output is correct
26	Correct	4 ms	15964 KB	Output is correct
27	Correct	4 ms	15964 KB	Output is correct
28	Correct	4 ms	15964 KB	Output is correct
29	Correct	5 ms	15708 KB	Output is correct
30	Correct	3 ms	15708 KB	Output is correct
31	Correct	4 ms	15964 KB	Output is correct
32	Correct	4 ms	15960 KB	Output is correct
33	Correct	3 ms	15708 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	15708 KB	Output is correct
37	Correct	3 ms	15708 KB	Output is correct
38	Correct	4 ms	15964 KB	Output is correct
39	Correct	4 ms	15708 KB	Output is correct
40	Correct	3 ms	15708 KB	Output is correct
41	Correct	3 ms	15708 KB	Output is correct
42	Correct	4 ms	15708 KB	Output is correct
43	Correct	3 ms	15964 KB	Output is correct
44	Correct	3 ms	15708 KB	Output is correct
45	Correct	3 ms	15708 KB	Output is correct
46	Correct	3 ms	15704 KB	Output is correct
47	Correct	3 ms	15708 KB	Output is correct
48	Correct	3 ms	15708 KB	Output is correct
49	Correct	4 ms	15964 KB	Output is correct
50	Correct	3 ms	15708 KB	Output is correct
51	Correct	3 ms	15708 KB	Output is correct
52	Correct	3 ms	15708 KB	Output is correct
53	Correct	3 ms	15708 KB	Output is correct
54	Correct	3 ms	15704 KB	Output is correct
55	Correct	3 ms	15704 KB	Output is correct
56	Correct	3 ms	15708 KB	Output is correct
57	Correct	3 ms	15708 KB	Output is correct
58	Correct	4 ms	15964 KB	Output is correct

Subtask #3
37.0 / 37.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	4 ms	16008 KB	Output is correct
2	Correct	4 ms	15708 KB	Output is correct
3	Correct	3 ms	15708 KB	Output is correct
4	Correct	3 ms	15708 KB	Output is correct
5	Correct	4 ms	15704 KB	Output is correct
6	Correct	3 ms	15708 KB	Output is correct
7	Correct	3 ms	15708 KB	Output is correct
8	Correct	4 ms	15708 KB	Output is correct
9	Correct	4 ms	15816 KB	Output is correct
10	Correct	4 ms	15708 KB	Output is correct
11	Correct	3 ms	15708 KB	Output is correct
12	Correct	3 ms	15708 KB	Output is correct
13	Correct	3 ms	15852 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	15708 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	3 ms	15708 KB	Output is correct
21	Correct	3 ms	15964 KB	Output is correct
22	Correct	4 ms	15964 KB	Output is correct
23	Correct	4 ms	15964 KB	Output is correct
24	Correct	4 ms	15964 KB	Output is correct
25	Correct	4 ms	15964 KB	Output is correct
26	Correct	4 ms	15964 KB	Output is correct
27	Correct	4 ms	15964 KB	Output is correct
28	Correct	4 ms	15964 KB	Output is correct
29	Correct	5 ms	15708 KB	Output is correct
30	Correct	3 ms	15708 KB	Output is correct
31	Correct	4 ms	15964 KB	Output is correct
32	Correct	4 ms	15960 KB	Output is correct
33	Correct	3 ms	15708 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	15708 KB	Output is correct
37	Correct	3 ms	15708 KB	Output is correct
38	Correct	4 ms	15964 KB	Output is correct
39	Correct	4 ms	15708 KB	Output is correct
40	Correct	3 ms	15708 KB	Output is correct
41	Correct	3 ms	15708 KB	Output is correct
42	Correct	4 ms	15708 KB	Output is correct
43	Correct	3 ms	15964 KB	Output is correct
44	Correct	3 ms	15708 KB	Output is correct
45	Correct	3 ms	15708 KB	Output is correct
46	Correct	3 ms	15704 KB	Output is correct
47	Correct	3 ms	15708 KB	Output is correct
48	Correct	3 ms	15708 KB	Output is correct
49	Correct	4 ms	15964 KB	Output is correct
50	Correct	3 ms	15708 KB	Output is correct
51	Correct	3 ms	15708 KB	Output is correct
52	Correct	3 ms	15708 KB	Output is correct
53	Correct	3 ms	15708 KB	Output is correct
54	Correct	3 ms	15704 KB	Output is correct
55	Correct	3 ms	15704 KB	Output is correct
56	Correct	3 ms	15708 KB	Output is correct
57	Correct	3 ms	15708 KB	Output is correct
58	Correct	4 ms	15964 KB	Output is correct
59	Correct	381 ms	47584 KB	Output is correct
60	Correct	365 ms	39768 KB	Output is correct
61	Correct	3 ms	15708 KB	Output is correct
62	Correct	3 ms	15708 KB	Output is correct
63	Correct	299 ms	41880 KB	Output is correct
64	Correct	5 ms	16476 KB	Output is correct
65	Correct	12 ms	21084 KB	Output is correct
66	Correct	103 ms	44952 KB	Output is correct
67	Correct	486 ms	67156 KB	Output is correct
68	Correct	529 ms	70652 KB	Output is correct
69	Correct	12 ms	17300 KB	Output is correct
70	Correct	75 ms	35652 KB	Output is correct
71	Correct	327 ms	77084 KB	Output is correct
72	Correct	336 ms	74736 KB	Output is correct
73	Correct	54 ms	25292 KB	Output is correct
74	Correct	393 ms	44820 KB	Output is correct
75	Correct	27 ms	24072 KB	Output is correct
76	Correct	333 ms	76572 KB	Output is correct
77	Correct	337 ms	76820 KB	Output is correct
78	Correct	25 ms	22928 KB	Output is correct
79	Correct	544 ms	69204 KB	Output is correct
80	Correct	5 ms	16220 KB	Output is correct
81	Correct	83 ms	33428 KB	Output is correct
82	Correct	378 ms	61976 KB	Output is correct
83	Correct	421 ms	45000 KB	Output is correct
84	Correct	403 ms	45056 KB	Output is correct
85	Correct	421 ms	45180 KB	Output is correct
86	Correct	408 ms	46436 KB	Output is correct
87	Correct	370 ms	46816 KB	Output is correct

Submission #848230

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