#include "bits/stdc++.h"
using namespace std;
typedef long long ll;
typedef vector<int>vi;
#define pb push_back
#define sz(v) (int)v.size()
typedef string str;
#define FOR(i,a,b) for(int i=a; i<b; i++)
void IO(){
#ifdef LOCAL
freopen("input.txt","r",stdin);
freopen("output.txt","w",stdout);
#endif
}
//------------------------------------------------------//
void ckmin(int &x, int y){x=min(x,y);}
const int MX=2e5;
int N;
vi out(MX),in(MX,0);
map<str,int>mp;
vi vis(MX,0);
int main(){
IO();
cin>>N;
int cnt=0;
FOR(i,0,N){
str s,ss; cin>>s>>ss;
if(!mp.count(s)) mp[s]=cnt++;
if(!mp.count(ss)) mp[ss]=cnt++;
out[mp[s]]=mp[ss];
if(s!=ss) in[mp[ss]]++;
}
if(N&1){
cout << -1 << endl;
return 0;
}
FOR(i,0,N) if(out[i]!=i && out[out[i]]==i) vis[i]=1,vis[out[i]]=1;
set<int>s;
FOR(i,0,N) if(in[i]==0) s.insert(i);
int ans=0;
while(sz(s)){
auto it=s.begin();
int u=*it;
s.erase(it);
if(out[u]==u) continue;
if(!vis[out[u]]){
if(out[out[u]]!=out[u]){
in[out[out[u]]]--;
if(in[out[out[u]]]==0) s.insert(out[out[u]]);
}
vis[u]=1; vis[out[u]]=1;
out[out[u]]=u;
ans++;
}
}
FOR(i,0,N){
int n=0,cur=i;
while(!vis[cur]){
vis[cur]=1; n++;
cur=out[cur];
}
if(n!=2) ans+=(n+1)/2;
}
cout << ans << endl;
}
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
2 ms |
2636 KB |
Output is correct |
2 |
Correct |
2 ms |
2636 KB |
Output is correct |
3 |
Correct |
2 ms |
2636 KB |
Output is correct |
4 |
Correct |
2 ms |
2636 KB |
Output is correct |
5 |
Correct |
2 ms |
2636 KB |
Output is correct |
6 |
Correct |
2 ms |
2636 KB |
Output is correct |
7 |
Correct |
2 ms |
2636 KB |
Output is correct |
8 |
Correct |
2 ms |
2636 KB |
Output is correct |
9 |
Correct |
2 ms |
2664 KB |
Output is correct |
10 |
Correct |
2 ms |
2636 KB |
Output is correct |
11 |
Correct |
2 ms |
2660 KB |
Output is correct |
12 |
Correct |
2 ms |
2636 KB |
Output is correct |
13 |
Correct |
2 ms |
2668 KB |
Output is correct |
14 |
Correct |
2 ms |
2660 KB |
Output is correct |
15 |
Correct |
2 ms |
2660 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
2 ms |
2636 KB |
Output is correct |
2 |
Correct |
2 ms |
2636 KB |
Output is correct |
3 |
Correct |
2 ms |
2636 KB |
Output is correct |
4 |
Correct |
298 ms |
10544 KB |
Output is correct |
5 |
Correct |
312 ms |
10572 KB |
Output is correct |
6 |
Correct |
327 ms |
10512 KB |
Output is correct |
7 |
Correct |
312 ms |
10556 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
313 ms |
11696 KB |
Output is correct |
2 |
Correct |
310 ms |
11260 KB |
Output is correct |
3 |
Correct |
256 ms |
15176 KB |
Output is correct |
4 |
Correct |
296 ms |
10524 KB |
Output is correct |
5 |
Correct |
296 ms |
10428 KB |
Output is correct |
6 |
Correct |
327 ms |
12980 KB |
Output is correct |
7 |
Correct |
299 ms |
12852 KB |
Output is correct |
8 |
Correct |
289 ms |
13436 KB |
Output is correct |
9 |
Correct |
301 ms |
13872 KB |
Output is correct |
10 |
Correct |
260 ms |
15172 KB |
Output is correct |
11 |
Correct |
2 ms |
2636 KB |
Output is correct |
12 |
Correct |
2 ms |
2636 KB |
Output is correct |
13 |
Correct |
2 ms |
2636 KB |
Output is correct |
14 |
Correct |
2 ms |
2636 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
2 ms |
2636 KB |
Output is correct |
2 |
Correct |
2 ms |
2636 KB |
Output is correct |
3 |
Correct |
2 ms |
2636 KB |
Output is correct |
4 |
Correct |
2 ms |
2636 KB |
Output is correct |
5 |
Correct |
2 ms |
2636 KB |
Output is correct |
6 |
Correct |
2 ms |
2636 KB |
Output is correct |
7 |
Correct |
2 ms |
2636 KB |
Output is correct |
8 |
Correct |
2 ms |
2636 KB |
Output is correct |
9 |
Correct |
2 ms |
2664 KB |
Output is correct |
10 |
Correct |
2 ms |
2636 KB |
Output is correct |
11 |
Correct |
2 ms |
2660 KB |
Output is correct |
12 |
Correct |
2 ms |
2636 KB |
Output is correct |
13 |
Correct |
2 ms |
2668 KB |
Output is correct |
14 |
Correct |
2 ms |
2660 KB |
Output is correct |
15 |
Correct |
2 ms |
2660 KB |
Output is correct |
16 |
Correct |
2 ms |
2636 KB |
Output is correct |
17 |
Correct |
2 ms |
2636 KB |
Output is correct |
18 |
Correct |
2 ms |
2636 KB |
Output is correct |
19 |
Correct |
298 ms |
10544 KB |
Output is correct |
20 |
Correct |
312 ms |
10572 KB |
Output is correct |
21 |
Correct |
327 ms |
10512 KB |
Output is correct |
22 |
Correct |
312 ms |
10556 KB |
Output is correct |
23 |
Correct |
313 ms |
11696 KB |
Output is correct |
24 |
Correct |
310 ms |
11260 KB |
Output is correct |
25 |
Correct |
256 ms |
15176 KB |
Output is correct |
26 |
Correct |
296 ms |
10524 KB |
Output is correct |
27 |
Correct |
296 ms |
10428 KB |
Output is correct |
28 |
Correct |
327 ms |
12980 KB |
Output is correct |
29 |
Correct |
299 ms |
12852 KB |
Output is correct |
30 |
Correct |
289 ms |
13436 KB |
Output is correct |
31 |
Correct |
301 ms |
13872 KB |
Output is correct |
32 |
Correct |
260 ms |
15172 KB |
Output is correct |
33 |
Correct |
2 ms |
2636 KB |
Output is correct |
34 |
Correct |
2 ms |
2636 KB |
Output is correct |
35 |
Correct |
2 ms |
2636 KB |
Output is correct |
36 |
Correct |
2 ms |
2636 KB |
Output is correct |
37 |
Correct |
316 ms |
13044 KB |
Output is correct |
38 |
Correct |
311 ms |
14744 KB |
Output is correct |
39 |
Correct |
338 ms |
14764 KB |
Output is correct |
40 |
Correct |
354 ms |
14940 KB |
Output is correct |
41 |
Correct |
314 ms |
14968 KB |
Output is correct |
42 |
Correct |
365 ms |
14288 KB |
Output is correct |
43 |
Correct |
312 ms |
14284 KB |
Output is correct |
44 |
Correct |
312 ms |
14336 KB |
Output is correct |
45 |
Correct |
315 ms |
14332 KB |
Output is correct |
46 |
Correct |
323 ms |
14312 KB |
Output is correct |
47 |
Correct |
312 ms |
15924 KB |
Output is correct |
48 |
Correct |
322 ms |
13752 KB |
Output is correct |
49 |
Correct |
315 ms |
13252 KB |
Output is correct |
50 |
Correct |
267 ms |
17248 KB |
Output is correct |
51 |
Correct |
304 ms |
12604 KB |
Output is correct |
52 |
Correct |
350 ms |
12612 KB |
Output is correct |
53 |
Correct |
317 ms |
14904 KB |
Output is correct |
54 |
Correct |
383 ms |
14960 KB |
Output is correct |
55 |
Correct |
356 ms |
15532 KB |
Output is correct |
56 |
Correct |
314 ms |
15960 KB |
Output is correct |
57 |
Correct |
255 ms |
17220 KB |
Output is correct |
58 |
Correct |
2 ms |
2636 KB |
Output is correct |
59 |
Correct |
2 ms |
2644 KB |
Output is correct |
60 |
Correct |
2 ms |
2636 KB |
Output is correct |
61 |
Correct |
2 ms |
2660 KB |
Output is correct |
62 |
Correct |
2 ms |
2636 KB |
Output is correct |
63 |
Correct |
2 ms |
2636 KB |
Output is correct |
64 |
Correct |
2 ms |
2664 KB |
Output is correct |
65 |
Correct |
322 ms |
12664 KB |
Output is correct |
66 |
Correct |
347 ms |
12660 KB |
Output is correct |
67 |
Correct |
316 ms |
12520 KB |
Output is correct |
68 |
Correct |
306 ms |
12628 KB |
Output is correct |
69 |
Correct |
2 ms |
2636 KB |
Output is correct |
70 |
Correct |
2 ms |
2636 KB |
Output is correct |
71 |
Correct |
3 ms |
2636 KB |
Output is correct |
72 |
Correct |
2 ms |
2636 KB |
Output is correct |
73 |
Correct |
3 ms |
2636 KB |
Output is correct |
74 |
Correct |
2 ms |
2636 KB |
Output is correct |
75 |
Correct |
2 ms |
2664 KB |
Output is correct |
76 |
Correct |
3 ms |
2636 KB |
Output is correct |
77 |
Correct |
2 ms |
2636 KB |
Output is correct |
78 |
Correct |
2 ms |
2636 KB |
Output is correct |
79 |
Correct |
2 ms |
2636 KB |
Output is correct |
80 |
Correct |
2 ms |
2636 KB |
Output is correct |
81 |
Correct |
2 ms |
2636 KB |
Output is correct |
82 |
Correct |
2 ms |
2636 KB |
Output is correct |
83 |
Correct |
2 ms |
2636 KB |
Output is correct |