#include<bits/stdc++.h>
using namespace std;
int main(){
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int n;
cin>>n;
map<string,int>mp;
vector<int>cnt(n+1);
vector<vector<int>>revadj(n+1);
vector<pair<string,string>>all(n);
for(int i=0;i<n;i++){
cin>>all[i].first>>all[i].second;
mp[all[i].first]=i;
}
vector<int>adj(n+1);
for(int i=0;i<n;i++){
int x=mp[all[i].second];
revadj[x].push_back(i);
adj[i]=x;
cnt[x]++;
}
if(n&1){
cout<<-1<<"\n";
return 0;
}
int res=n;
set<pair<int,int>>st;
vector<int>visa(n+1);
for(int i=0;i<n;i++){
if(adj[i]!=i&&adj[adj[i]]==i){
res--;
visa[i]=1;
continue;
}
st.insert(make_pair(cnt[i],i));
}
while((int)st.size()>0){
auto x=*st.begin();
if(x.first>=1){
vector<int>vis(n+2);
for(int i=0;i<n;i++){
if(st.count(make_pair(cnt[i],i))==0){
vis[i]=1;
}
}
for(int i=0;i<n;i++){
if(vis[i]==0){
int cnta=0;
int fi=i;
while(vis[fi]==0){
vis[fi]=1;
cnta++;
// cout<<fi<<" "<<adj[fi]<<'\n';
fi=adj[fi];
}
if(cnta==2){
res-=cnta;
continue;
}
//cout<<i<<" "<<cnt<<"\n";
res-=(cnta)/2;
}
}
break;
}
st.erase(x);
//cout<<x.second<<" "<<adj[x.second]<<'\n';
if(adj[x.second]==x.second||visa[adj[x.second]]){
continue;
}
res--;
for(auto y:revadj[x.second]){
st.erase(make_pair(cnt[y],y));
}
// cout<<x.second<<'\n';
st.erase(make_pair(cnt[adj[x.second]],adj[x.second]));
if(st.count(make_pair(cnt[adj[adj[x.second]]],adj[adj[x.second]]))==1){
st.erase(make_pair(cnt[adj[adj[x.second]]],adj[adj[x.second]]));
cnt[adj[adj[x.second]]]--;
st.insert(make_pair(cnt[adj[adj[x.second]]],adj[adj[x.second]]));
}
for(auto y:revadj[adj[x.second]]){
st.erase(make_pair(cnt[y],y));
}
}
cout<<res<<'\n';
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
212 KB |
Output is correct |
2 |
Correct |
1 ms |
212 KB |
Output is correct |
3 |
Correct |
1 ms |
212 KB |
Output is correct |
4 |
Correct |
1 ms |
212 KB |
Output is correct |
5 |
Correct |
1 ms |
212 KB |
Output is correct |
6 |
Correct |
1 ms |
320 KB |
Output is correct |
7 |
Correct |
0 ms |
212 KB |
Output is correct |
8 |
Correct |
1 ms |
212 KB |
Output is correct |
9 |
Correct |
0 ms |
212 KB |
Output is correct |
10 |
Correct |
1 ms |
292 KB |
Output is correct |
11 |
Correct |
0 ms |
212 KB |
Output is correct |
12 |
Correct |
1 ms |
212 KB |
Output is correct |
13 |
Correct |
1 ms |
212 KB |
Output is correct |
14 |
Correct |
1 ms |
212 KB |
Output is correct |
15 |
Correct |
0 ms |
320 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
212 KB |
Output is correct |
2 |
Correct |
1 ms |
316 KB |
Output is correct |
3 |
Correct |
1 ms |
320 KB |
Output is correct |
4 |
Correct |
175 ms |
26540 KB |
Output is correct |
5 |
Correct |
175 ms |
26096 KB |
Output is correct |
6 |
Correct |
174 ms |
26300 KB |
Output is correct |
7 |
Correct |
138 ms |
20880 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
254 ms |
26124 KB |
Output is correct |
2 |
Correct |
238 ms |
25728 KB |
Output is correct |
3 |
Correct |
149 ms |
26564 KB |
Output is correct |
4 |
Correct |
161 ms |
19636 KB |
Output is correct |
5 |
Correct |
229 ms |
26244 KB |
Output is correct |
6 |
Correct |
226 ms |
24776 KB |
Output is correct |
7 |
Correct |
217 ms |
25076 KB |
Output is correct |
8 |
Correct |
184 ms |
25484 KB |
Output is correct |
9 |
Correct |
193 ms |
24160 KB |
Output is correct |
10 |
Correct |
125 ms |
23536 KB |
Output is correct |
11 |
Correct |
1 ms |
320 KB |
Output is correct |
12 |
Correct |
1 ms |
212 KB |
Output is correct |
13 |
Correct |
1 ms |
212 KB |
Output is correct |
14 |
Correct |
1 ms |
316 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
212 KB |
Output is correct |
2 |
Correct |
1 ms |
212 KB |
Output is correct |
3 |
Correct |
1 ms |
212 KB |
Output is correct |
4 |
Correct |
1 ms |
212 KB |
Output is correct |
5 |
Correct |
1 ms |
212 KB |
Output is correct |
6 |
Correct |
1 ms |
320 KB |
Output is correct |
7 |
Correct |
0 ms |
212 KB |
Output is correct |
8 |
Correct |
1 ms |
212 KB |
Output is correct |
9 |
Correct |
0 ms |
212 KB |
Output is correct |
10 |
Correct |
1 ms |
292 KB |
Output is correct |
11 |
Correct |
0 ms |
212 KB |
Output is correct |
12 |
Correct |
1 ms |
212 KB |
Output is correct |
13 |
Correct |
1 ms |
212 KB |
Output is correct |
14 |
Correct |
1 ms |
212 KB |
Output is correct |
15 |
Correct |
0 ms |
320 KB |
Output is correct |
16 |
Correct |
1 ms |
212 KB |
Output is correct |
17 |
Correct |
1 ms |
316 KB |
Output is correct |
18 |
Correct |
1 ms |
320 KB |
Output is correct |
19 |
Correct |
175 ms |
26540 KB |
Output is correct |
20 |
Correct |
175 ms |
26096 KB |
Output is correct |
21 |
Correct |
174 ms |
26300 KB |
Output is correct |
22 |
Correct |
138 ms |
20880 KB |
Output is correct |
23 |
Correct |
254 ms |
26124 KB |
Output is correct |
24 |
Correct |
238 ms |
25728 KB |
Output is correct |
25 |
Correct |
149 ms |
26564 KB |
Output is correct |
26 |
Correct |
161 ms |
19636 KB |
Output is correct |
27 |
Correct |
229 ms |
26244 KB |
Output is correct |
28 |
Correct |
226 ms |
24776 KB |
Output is correct |
29 |
Correct |
217 ms |
25076 KB |
Output is correct |
30 |
Correct |
184 ms |
25484 KB |
Output is correct |
31 |
Correct |
193 ms |
24160 KB |
Output is correct |
32 |
Correct |
125 ms |
23536 KB |
Output is correct |
33 |
Correct |
1 ms |
320 KB |
Output is correct |
34 |
Correct |
1 ms |
212 KB |
Output is correct |
35 |
Correct |
1 ms |
212 KB |
Output is correct |
36 |
Correct |
1 ms |
316 KB |
Output is correct |
37 |
Correct |
216 ms |
25912 KB |
Output is correct |
38 |
Correct |
257 ms |
24956 KB |
Output is correct |
39 |
Correct |
233 ms |
25116 KB |
Output is correct |
40 |
Correct |
227 ms |
26344 KB |
Output is correct |
41 |
Correct |
219 ms |
26544 KB |
Output is correct |
42 |
Correct |
234 ms |
26700 KB |
Output is correct |
43 |
Correct |
233 ms |
26780 KB |
Output is correct |
44 |
Correct |
231 ms |
26792 KB |
Output is correct |
45 |
Correct |
275 ms |
26708 KB |
Output is correct |
46 |
Correct |
297 ms |
26832 KB |
Output is correct |
47 |
Correct |
195 ms |
25928 KB |
Output is correct |
48 |
Correct |
289 ms |
27468 KB |
Output is correct |
49 |
Correct |
238 ms |
27440 KB |
Output is correct |
50 |
Correct |
165 ms |
28380 KB |
Output is correct |
51 |
Correct |
143 ms |
21284 KB |
Output is correct |
52 |
Correct |
249 ms |
27912 KB |
Output is correct |
53 |
Correct |
209 ms |
26400 KB |
Output is correct |
54 |
Correct |
261 ms |
26776 KB |
Output is correct |
55 |
Correct |
280 ms |
27012 KB |
Output is correct |
56 |
Correct |
193 ms |
25800 KB |
Output is correct |
57 |
Correct |
135 ms |
25096 KB |
Output is correct |
58 |
Correct |
1 ms |
212 KB |
Output is correct |
59 |
Correct |
1 ms |
316 KB |
Output is correct |
60 |
Correct |
1 ms |
212 KB |
Output is correct |
61 |
Correct |
1 ms |
212 KB |
Output is correct |
62 |
Correct |
1 ms |
212 KB |
Output is correct |
63 |
Correct |
1 ms |
320 KB |
Output is correct |
64 |
Correct |
0 ms |
316 KB |
Output is correct |
65 |
Correct |
170 ms |
28276 KB |
Output is correct |
66 |
Correct |
184 ms |
28080 KB |
Output is correct |
67 |
Correct |
201 ms |
28280 KB |
Output is correct |
68 |
Correct |
148 ms |
22812 KB |
Output is correct |
69 |
Correct |
1 ms |
212 KB |
Output is correct |
70 |
Correct |
1 ms |
212 KB |
Output is correct |
71 |
Correct |
1 ms |
212 KB |
Output is correct |
72 |
Correct |
1 ms |
212 KB |
Output is correct |
73 |
Correct |
1 ms |
316 KB |
Output is correct |
74 |
Correct |
1 ms |
212 KB |
Output is correct |
75 |
Correct |
1 ms |
212 KB |
Output is correct |
76 |
Correct |
1 ms |
212 KB |
Output is correct |
77 |
Correct |
1 ms |
212 KB |
Output is correct |
78 |
Correct |
1 ms |
320 KB |
Output is correct |
79 |
Correct |
1 ms |
212 KB |
Output is correct |
80 |
Correct |
1 ms |
320 KB |
Output is correct |
81 |
Correct |
0 ms |
320 KB |
Output is correct |
82 |
Correct |
0 ms |
212 KB |
Output is correct |
83 |
Correct |
1 ms |
212 KB |
Output is correct |