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Submission #108713

# Submission time Handle Problem Language Result Execution time Memory
108713 2019-05-01T06:48:44 Z ckodser Network (BOI15_net) C++14
100 / 100
 1369 ms 105848 KB 
#include<bits/stdc++.h>

#define ll long long
#define pb push_back
#define mp make_pair
#define ld long double
#define F first
#define S second
#define pii pair<ll,ll> 

using namespace :: std;

const ll mod=1e9+7;
const ll maxn=5e5+500;
const ll inf=1e9+900;

vector<ll> ger[maxn];
set<pii> st;
vector<ll> barg;

pii dfs(ll a,ll p=-1){
    if(ger[a].size()==1){
	barg.pb(a);
	return mp(a,-1);
    }
    vector<pii> vec2;
    vector<ll> vec1;
    for(auto v:ger[a]){
	if(v!=p){
	    pii r=dfs(v,a);
	    if(r.S==-1)vec1.pb(r.F);
	    else       vec2.pb(r);
	}
    }
    if(vec2.size()==1){
	if(vec1.empty()){
	    return vec2.back();
	}else{
	    pii e=vec2.back();
	    st.erase(e);
	    ll v=vec1.back();
	    vec1.pop_back();
	    st.insert(mp(e.F,v));
	    pii las=mp(e.F,v);
	    vec1.pb(e.S);
	    for(ll i=0;i+1<vec1.size();i+=2){
		st.insert(mp(vec1[i],vec1[i+1]));
	    }
	    if(vec1.size()%2==1){
		return mp(vec1.back(),-1);
	    }
	    else{
		return las;
	    }
	}
    }else{
	pii las;
	for(auto e:vec2){
	    st.erase(e);
	}
	for(ll i=0;i<vec2.size();i++){
	    pii e=mp(vec2[i].S,vec2[(i+1)%vec2.size()].F);
	    las=e;
	    st.insert(e);
	}
	for(ll i=0;i+1<vec1.size();i+=2){
	    st.insert(mp(vec1[i],vec1[i+1]));
	    las=mp(vec1[i],vec1[i+1]);
	}
	if(vec1.size()%2==1){
	    return mp(vec1.back(),-1);
	}
	else{
	    return las;
	}
    }
}
int main(){
    ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
    ll n;
    cin>>n;
    for(ll i=1;i<n;i++){
	ll v,u;
	cin>>v>>u;
	ger[u].pb(v);
	ger[v].pb(u);
    }
    ll rot;
    for(ll i=1;i<=n;i++){
	if(ger[i].size()>1)rot=i;
    }
    pii r=dfs(rot);
    if(r.S==-1 && r.F!=-1){
	ll v=r.F;
	for(auto u:barg){
	    if(v!=u){
		st.insert(mp(u,v));
		break;
	    }
	}
    }		
    cout<<st.size()<<endl;
    for(auto e:st){
	cout<<e.F<<' '<<e.S<<endl;
    }	
}

Compilation message

net.cpp: In function 'std::pair<long long int, long long int> dfs(long long int, long long int)':
net.cpp:46:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
      for(ll i=0;i+1<vec1.size();i+=2){
                 ~~~^~~~~~~~~~~~
net.cpp:61:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(ll i=0;i<vec2.size();i++){
             ~^~~~~~~~~~~~
net.cpp:66:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(ll i=0;i+1<vec1.size();i+=2){
             ~~~^~~~~~~~~~~~
net.cpp: In function 'int main()':
net.cpp:92:18: warning: 'rot' may be used uninitialized in this function [-Wmaybe-uninitialized]
     pii r=dfs(rot);
                  ^

Subtask #1
18.0 / 18.0

# Verdict Execution time Memory Grader output
1 Correct 12 ms 12160 KB Output is correct
2 Correct 12 ms 12160 KB Output is correct
3 Correct 12 ms 12032 KB Output is correct
4 Correct 12 ms 12032 KB Output is correct
5 Correct 14 ms 12160 KB Output is correct
6 Correct 14 ms 12160 KB Output is correct
7 Correct 13 ms 12160 KB Output is correct
8 Correct 13 ms 12032 KB Output is correct
9 Correct 13 ms 12032 KB Output is correct
10 Correct 13 ms 12032 KB Output is correct
11 Correct 13 ms 12160 KB Output is correct
12 Correct 15 ms 12160 KB Output is correct
13 Correct 14 ms 12236 KB Output is correct
14 Correct 12 ms 12032 KB Output is correct
15 Correct 12 ms 12160 KB Output is correct
16 Correct 14 ms 12032 KB Output is correct
17 Correct 14 ms 12160 KB Output is correct
18 Correct 14 ms 12160 KB Output is correct
19 Correct 15 ms 12032 KB Output is correct
20 Correct 14 ms 12160 KB Output is correct

Subtask #2
45.0 / 45.0

# Verdict Execution time Memory Grader output
1 Correct 12 ms 12160 KB Output is correct
2 Correct 12 ms 12160 KB Output is correct
3 Correct 12 ms 12032 KB Output is correct
4 Correct 12 ms 12032 KB Output is correct
5 Correct 14 ms 12160 KB Output is correct
6 Correct 14 ms 12160 KB Output is correct
7 Correct 13 ms 12160 KB Output is correct
8 Correct 13 ms 12032 KB Output is correct
9 Correct 13 ms 12032 KB Output is correct
10 Correct 13 ms 12032 KB Output is correct
11 Correct 13 ms 12160 KB Output is correct
12 Correct 15 ms 12160 KB Output is correct
13 Correct 14 ms 12236 KB Output is correct
14 Correct 12 ms 12032 KB Output is correct
15 Correct 12 ms 12160 KB Output is correct
16 Correct 14 ms 12032 KB Output is correct
17 Correct 14 ms 12160 KB Output is correct
18 Correct 14 ms 12160 KB Output is correct
19 Correct 15 ms 12032 KB Output is correct
20 Correct 14 ms 12160 KB Output is correct
21 Correct 12 ms 12160 KB Output is correct
22 Correct 15 ms 12312 KB Output is correct
23 Correct 15 ms 12416 KB Output is correct
24 Correct 16 ms 12288 KB Output is correct
25 Correct 13 ms 12288 KB Output is correct
26 Correct 14 ms 12160 KB Output is correct
27 Correct 14 ms 12032 KB Output is correct
28 Correct 15 ms 12288 KB Output is correct
29 Correct 15 ms 12160 KB Output is correct
30 Correct 14 ms 12160 KB Output is correct
31 Correct 17 ms 12288 KB Output is correct
32 Correct 13 ms 12160 KB Output is correct
33 Correct 13 ms 12032 KB Output is correct
34 Correct 18 ms 12032 KB Output is correct
35 Correct 14 ms 12160 KB Output is correct
36 Correct 14 ms 12160 KB Output is correct
37 Correct 15 ms 12140 KB Output is correct
38 Correct 13 ms 12288 KB Output is correct
39 Correct 14 ms 12160 KB Output is correct
40 Correct 13 ms 12160 KB Output is correct
41 Correct 14 ms 12160 KB Output is correct
42 Correct 14 ms 12160 KB Output is correct
43 Correct 15 ms 12160 KB Output is correct
44 Correct 14 ms 12032 KB Output is correct
45 Correct 15 ms 12160 KB Output is correct
46 Correct 19 ms 12160 KB Output is correct
47 Correct 14 ms 12032 KB Output is correct
48 Correct 17 ms 12160 KB Output is correct
49 Correct 15 ms 12160 KB Output is correct
50 Correct 17 ms 12032 KB Output is correct
51 Correct 13 ms 12032 KB Output is correct
52 Correct 15 ms 12160 KB Output is correct
53 Correct 15 ms 12288 KB Output is correct
54 Correct 13 ms 12032 KB Output is correct
55 Correct 14 ms 12160 KB Output is correct
56 Correct 14 ms 12072 KB Output is correct
57 Correct 14 ms 12160 KB Output is correct
58 Correct 17 ms 12284 KB Output is correct

Subtask #3
37.0 / 37.0

# Verdict Execution time Memory Grader output
1 Correct 12 ms 12160 KB Output is correct
2 Correct 12 ms 12160 KB Output is correct
3 Correct 12 ms 12032 KB Output is correct
4 Correct 12 ms 12032 KB Output is correct
5 Correct 14 ms 12160 KB Output is correct
6 Correct 14 ms 12160 KB Output is correct
7 Correct 13 ms 12160 KB Output is correct
8 Correct 13 ms 12032 KB Output is correct
9 Correct 13 ms 12032 KB Output is correct
10 Correct 13 ms 12032 KB Output is correct
11 Correct 13 ms 12160 KB Output is correct
12 Correct 15 ms 12160 KB Output is correct
13 Correct 14 ms 12236 KB Output is correct
14 Correct 12 ms 12032 KB Output is correct
15 Correct 12 ms 12160 KB Output is correct
16 Correct 14 ms 12032 KB Output is correct
17 Correct 14 ms 12160 KB Output is correct
18 Correct 14 ms 12160 KB Output is correct
19 Correct 15 ms 12032 KB Output is correct
20 Correct 14 ms 12160 KB Output is correct
21 Correct 12 ms 12160 KB Output is correct
22 Correct 15 ms 12312 KB Output is correct
23 Correct 15 ms 12416 KB Output is correct
24 Correct 16 ms 12288 KB Output is correct
25 Correct 13 ms 12288 KB Output is correct
26 Correct 14 ms 12160 KB Output is correct
27 Correct 14 ms 12032 KB Output is correct
28 Correct 15 ms 12288 KB Output is correct
29 Correct 15 ms 12160 KB Output is correct
30 Correct 14 ms 12160 KB Output is correct
31 Correct 17 ms 12288 KB Output is correct
32 Correct 13 ms 12160 KB Output is correct
33 Correct 13 ms 12032 KB Output is correct
34 Correct 18 ms 12032 KB Output is correct
35 Correct 14 ms 12160 KB Output is correct
36 Correct 14 ms 12160 KB Output is correct
37 Correct 15 ms 12140 KB Output is correct
38 Correct 13 ms 12288 KB Output is correct
39 Correct 14 ms 12160 KB Output is correct
40 Correct 13 ms 12160 KB Output is correct
41 Correct 14 ms 12160 KB Output is correct
42 Correct 14 ms 12160 KB Output is correct
43 Correct 15 ms 12160 KB Output is correct
44 Correct 14 ms 12032 KB Output is correct
45 Correct 15 ms 12160 KB Output is correct
46 Correct 19 ms 12160 KB Output is correct
47 Correct 14 ms 12032 KB Output is correct
48 Correct 17 ms 12160 KB Output is correct
49 Correct 15 ms 12160 KB Output is correct
50 Correct 17 ms 12032 KB Output is correct
51 Correct 13 ms 12032 KB Output is correct
52 Correct 15 ms 12160 KB Output is correct
53 Correct 15 ms 12288 KB Output is correct
54 Correct 13 ms 12032 KB Output is correct
55 Correct 14 ms 12160 KB Output is correct
56 Correct 14 ms 12072 KB Output is correct
57 Correct 14 ms 12160 KB Output is correct
58 Correct 17 ms 12284 KB Output is correct
59 Correct 1226 ms 44704 KB Output is correct
60 Correct 1229 ms 47312 KB Output is correct
61 Correct 14 ms 12032 KB Output is correct
62 Correct 15 ms 12160 KB Output is correct
63 Correct 892 ms 41552 KB Output is correct
64 Correct 16 ms 12800 KB Output is correct
65 Correct 28 ms 15224 KB Output is correct
66 Correct 242 ms 35064 KB Output is correct
67 Correct 759 ms 105848 KB Output is correct
68 Correct 784 ms 82708 KB Output is correct
69 Correct 30 ms 13440 KB Output is correct
70 Correct 306 ms 26728 KB Output is correct
71 Correct 1144 ms 55288 KB Output is correct
72 Correct 1031 ms 52540 KB Output is correct
73 Correct 212 ms 20460 KB Output is correct
74 Correct 1029 ms 42268 KB Output is correct
75 Correct 107 ms 16828 KB Output is correct
76 Correct 1090 ms 55672 KB Output is correct
77 Correct 974 ms 56712 KB Output is correct
78 Correct 72 ms 17272 KB Output is correct
79 Correct 697 ms 63784 KB Output is correct
80 Correct 19 ms 12416 KB Output is correct
81 Correct 297 ms 24512 KB Output is correct
82 Correct 1175 ms 48492 KB Output is correct
83 Correct 1002 ms 42340 KB Output is correct
84 Correct 1065 ms 42484 KB Output is correct
85 Correct 1038 ms 42380 KB Output is correct
86 Correct 1369 ms 47400 KB Output is correct
87 Correct 1277 ms 47372 KB Output is correct