oj.uz

Submission #239849

# Submission time Handle Problem Language Result Execution time Memory
239849 2020-06-17T11:59:45 Z kshitij_sodani Network (BOI15_net) C++17
100 / 100
 827 ms 57720 KB 
#include <bits/stdc++.h>
using namespace std;
typedef int64_t llo;
#define mp make_pair
#define pb push_back
#define a first 
#define b second



int n;
vector<int> adj[500001];
int co=0;
vector<int> kk;
void dfs(int no,int par=-1){
	vector<pair<int,int>> ss[2];
	for(auto j:adj[no]){
		if(j!=par){
			dfs(j,no);
			/*cout<<j<<','<<x[0]<<","<<x[1]<<endl;
			if(x.size()==1){
				ss[0].pb({x[0],-1});
			}
			else{
				ss[1].pb({x[0],x[1]});
			}*/
		}
	}
	if(adj[no].size()==1){
		co+=1;
		kk.pb(no);
	}
/*	if(no==3){
		cout<<','<<ss[1].size()<<","<<ss[0].size()<<endl;
	}
	if(ss[1].size()%2==0){
		for(int i=0;i<(int)(ss[1].size());i+=2){
			ans.pb({ss[1][i].a,ss[1][i+1].a});
			ans.pb({ss[1][i].b,ss[1][i+1].b});

		}

		if(ss[0].size()==0){
			pair<int,int> x=ans.back();
			ans.pop_back();
			return {x.a,x.b};
		}

		for(int i=0;i<(int)(ss[0].size())-1;i+=2){
			ans.pb({ss[0][i].a,ss[0][i+1].a});
		}
		if(ss[0].size()%2==0){
			ans.pop_back();
			return {ss[0].back().a,ss[0][ss[0].size()-2].a};
		}
		else{
			return {ss[0].back().a};
		}
	}
	else{
		for(int i=0;i<(int)(ss[1].size())-1;i+=2){
			ans.pb({ss[1][i].a,ss[1][i+1].a});
			ans.pb({ss[1][i].b,ss[1][i+1].b});
		}
		for(int i=0;i<(int)(ss[0].size())-1;i+=2){
			ans.pb({ss[0][i].a,ss[0][i+1].a});
		}
		if(ss[0].size()%2==0){
			return {ss[1].back().a,ss[1].back().b};
		}
		else{
			ans.pb({ss[1].back().a,ss[0].back().a});
			return {ss[1].back().b};
		}
	}

*/

}
int main(){
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	cin>>n;
	for(int i=0;i<n-1;i++){
		int aa,bb;
		cin>>aa>>bb;
		adj[aa-1].pb(bb-1);
		adj[bb-1].pb(aa-1);

	}
	int r=0;
	for(int i=0;i<n;i++){
		if(adj[i].size()>1){
			r=i;
		}
	}
	dfs(r);
	cout<<(co+1)/2<<endl;

	for(int i=0;i<(co+1)/2;i++){
	//	cout<<i<<endl;
		cout<<kk[i]+1<<" "<<kk[i+co/2]+1<<endl;
	}
/*	for(int i=0;i<kk.size()/2;i++){
		cout<<kk[i]+1<<" "<<kk[kk.size()-i-1]+1<<endl;
	}
	if(kk.size()%2==1){
		cout<<kk[kk.size()/2]+1<<" "<<r+1<<endl;
	}*/


	return 0;
}

Subtask #1
18.0 / 18.0

# Verdict Execution time Memory Grader output
1 Correct 11 ms 12032 KB Output is correct
2 Correct 14 ms 12160 KB Output is correct
3 Correct 13 ms 12032 KB Output is correct
4 Correct 11 ms 12032 KB Output is correct
5 Correct 11 ms 12160 KB Output is correct
6 Correct 14 ms 12032 KB Output is correct
7 Correct 11 ms 12032 KB Output is correct
8 Correct 11 ms 12160 KB Output is correct
9 Correct 11 ms 12032 KB Output is correct
10 Correct 11 ms 12032 KB Output is correct
11 Correct 13 ms 12032 KB Output is correct
12 Correct 11 ms 12160 KB Output is correct
13 Correct 11 ms 11904 KB Output is correct
14 Correct 11 ms 12160 KB Output is correct
15 Correct 11 ms 12160 KB Output is correct
16 Correct 13 ms 12032 KB Output is correct
17 Correct 11 ms 12160 KB Output is correct
18 Correct 11 ms 12032 KB Output is correct
19 Correct 11 ms 12032 KB Output is correct
20 Correct 11 ms 12032 KB Output is correct

Subtask #2
45.0 / 45.0

# Verdict Execution time Memory Grader output
1 Correct 11 ms 12032 KB Output is correct
2 Correct 14 ms 12160 KB Output is correct
3 Correct 13 ms 12032 KB Output is correct
4 Correct 11 ms 12032 KB Output is correct
5 Correct 11 ms 12160 KB Output is correct
6 Correct 14 ms 12032 KB Output is correct
7 Correct 11 ms 12032 KB Output is correct
8 Correct 11 ms 12160 KB Output is correct
9 Correct 11 ms 12032 KB Output is correct
10 Correct 11 ms 12032 KB Output is correct
11 Correct 13 ms 12032 KB Output is correct
12 Correct 11 ms 12160 KB Output is correct
13 Correct 11 ms 11904 KB Output is correct
14 Correct 11 ms 12160 KB Output is correct
15 Correct 11 ms 12160 KB Output is correct
16 Correct 13 ms 12032 KB Output is correct
17 Correct 11 ms 12160 KB Output is correct
18 Correct 11 ms 12032 KB Output is correct
19 Correct 11 ms 12032 KB Output is correct
20 Correct 11 ms 12032 KB Output is correct
21 Correct 11 ms 12032 KB Output is correct
22 Correct 15 ms 12288 KB Output is correct
23 Correct 15 ms 12288 KB Output is correct
24 Correct 14 ms 12160 KB Output is correct
25 Correct 15 ms 12160 KB Output is correct
26 Correct 13 ms 12160 KB Output is correct
27 Correct 14 ms 12160 KB Output is correct
28 Correct 16 ms 12160 KB Output is correct
29 Correct 13 ms 12160 KB Output is correct
30 Correct 13 ms 12160 KB Output is correct
31 Correct 14 ms 12288 KB Output is correct
32 Correct 13 ms 12032 KB Output is correct
33 Correct 13 ms 12032 KB Output is correct
34 Correct 11 ms 12160 KB Output is correct
35 Correct 11 ms 12032 KB Output is correct
36 Correct 12 ms 12160 KB Output is correct
37 Correct 12 ms 12160 KB Output is correct
38 Correct 12 ms 12160 KB Output is correct
39 Correct 11 ms 12032 KB Output is correct
40 Correct 14 ms 12032 KB Output is correct
41 Correct 11 ms 12032 KB Output is correct
42 Correct 12 ms 12032 KB Output is correct
43 Correct 13 ms 12160 KB Output is correct
44 Correct 12 ms 12032 KB Output is correct
45 Correct 14 ms 12032 KB Output is correct
46 Correct 12 ms 12160 KB Output is correct
47 Correct 12 ms 12032 KB Output is correct
48 Correct 14 ms 12160 KB Output is correct
49 Correct 13 ms 12160 KB Output is correct
50 Correct 12 ms 12032 KB Output is correct
51 Correct 13 ms 12032 KB Output is correct
52 Correct 12 ms 12032 KB Output is correct
53 Correct 12 ms 12160 KB Output is correct
54 Correct 13 ms 12160 KB Output is correct
55 Correct 14 ms 12160 KB Output is correct
56 Correct 12 ms 12032 KB Output is correct
57 Correct 12 ms 12160 KB Output is correct
58 Correct 14 ms 12288 KB Output is correct

Subtask #3
37.0 / 37.0

# Verdict Execution time Memory Grader output
1 Correct 11 ms 12032 KB Output is correct
2 Correct 14 ms 12160 KB Output is correct
3 Correct 13 ms 12032 KB Output is correct
4 Correct 11 ms 12032 KB Output is correct
5 Correct 11 ms 12160 KB Output is correct
6 Correct 14 ms 12032 KB Output is correct
7 Correct 11 ms 12032 KB Output is correct
8 Correct 11 ms 12160 KB Output is correct
9 Correct 11 ms 12032 KB Output is correct
10 Correct 11 ms 12032 KB Output is correct
11 Correct 13 ms 12032 KB Output is correct
12 Correct 11 ms 12160 KB Output is correct
13 Correct 11 ms 11904 KB Output is correct
14 Correct 11 ms 12160 KB Output is correct
15 Correct 11 ms 12160 KB Output is correct
16 Correct 13 ms 12032 KB Output is correct
17 Correct 11 ms 12160 KB Output is correct
18 Correct 11 ms 12032 KB Output is correct
19 Correct 11 ms 12032 KB Output is correct
20 Correct 11 ms 12032 KB Output is correct
21 Correct 11 ms 12032 KB Output is correct
22 Correct 15 ms 12288 KB Output is correct
23 Correct 15 ms 12288 KB Output is correct
24 Correct 14 ms 12160 KB Output is correct
25 Correct 15 ms 12160 KB Output is correct
26 Correct 13 ms 12160 KB Output is correct
27 Correct 14 ms 12160 KB Output is correct
28 Correct 16 ms 12160 KB Output is correct
29 Correct 13 ms 12160 KB Output is correct
30 Correct 13 ms 12160 KB Output is correct
31 Correct 14 ms 12288 KB Output is correct
32 Correct 13 ms 12032 KB Output is correct
33 Correct 13 ms 12032 KB Output is correct
34 Correct 11 ms 12160 KB Output is correct
35 Correct 11 ms 12032 KB Output is correct
36 Correct 12 ms 12160 KB Output is correct
37 Correct 12 ms 12160 KB Output is correct
38 Correct 12 ms 12160 KB Output is correct
39 Correct 11 ms 12032 KB Output is correct
40 Correct 14 ms 12032 KB Output is correct
41 Correct 11 ms 12032 KB Output is correct
42 Correct 12 ms 12032 KB Output is correct
43 Correct 13 ms 12160 KB Output is correct
44 Correct 12 ms 12032 KB Output is correct
45 Correct 14 ms 12032 KB Output is correct
46 Correct 12 ms 12160 KB Output is correct
47 Correct 12 ms 12032 KB Output is correct
48 Correct 14 ms 12160 KB Output is correct
49 Correct 13 ms 12160 KB Output is correct
50 Correct 12 ms 12032 KB Output is correct
51 Correct 13 ms 12032 KB Output is correct
52 Correct 12 ms 12032 KB Output is correct
53 Correct 12 ms 12160 KB Output is correct
54 Correct 13 ms 12160 KB Output is correct
55 Correct 14 ms 12160 KB Output is correct
56 Correct 12 ms 12032 KB Output is correct
57 Correct 12 ms 12160 KB Output is correct
58 Correct 14 ms 12288 KB Output is correct
59 Correct 654 ms 36192 KB Output is correct
60 Correct 827 ms 38888 KB Output is correct
61 Correct 11 ms 12032 KB Output is correct
62 Correct 12 ms 12032 KB Output is correct
63 Correct 592 ms 33640 KB Output is correct
64 Correct 13 ms 12416 KB Output is correct
65 Correct 23 ms 13824 KB Output is correct
66 Correct 153 ms 25208 KB Output is correct
67 Correct 510 ms 57720 KB Output is correct
68 Correct 541 ms 50672 KB Output is correct
69 Correct 31 ms 13056 KB Output is correct
70 Correct 223 ms 21356 KB Output is correct
71 Correct 776 ms 42244 KB Output is correct
72 Correct 734 ms 40800 KB Output is correct
73 Correct 154 ms 19188 KB Output is correct
74 Correct 687 ms 37736 KB Output is correct
75 Correct 80 ms 15352 KB Output is correct
76 Correct 756 ms 41808 KB Output is correct
77 Correct 773 ms 41808 KB Output is correct
78 Correct 54 ms 15480 KB Output is correct
79 Correct 532 ms 45176 KB Output is correct
80 Correct 16 ms 12288 KB Output is correct
81 Correct 229 ms 21360 KB Output is correct
82 Correct 773 ms 39656 KB Output is correct
83 Correct 672 ms 37992 KB Output is correct
84 Correct 766 ms 37896 KB Output is correct
85 Correct 664 ms 37736 KB Output is correct
86 Correct 727 ms 38760 KB Output is correct
87 Correct 744 ms 39016 KB Output is correct