#include <bits/stdc++.h>
#pragma GCC optimize("O3")
using namespace std;
int main(){
cin.tie(0);
ios::sync_with_stdio(0);
int n, c = 0, sol = 0;
cin >> n;
if(n&1){
cout << "-1\n";
exit(0);
}
vector<int> love(n), deg(n), s, active(n, 1);
map<string,int> dns;
set<int> single;
for(int i = 0; i < n; i++){
single.insert(i);
string a, b;
cin >> a >> b;
if(!dns.count(a)) dns[a] = c++;
if(!dns.count(b)) dns[b] = c++;
love[dns[a]] = dns[b];
deg[dns[b]]++;
}
for(int i = 0; i < n; i++) if(deg[i] == 0) s.push_back(i);
int i = 0;
for(int j = 0; j < n; j++){
if(active[j] && love[love[j]] == j && love[j] != j){
active[j] = 0, active[love[j]] = 0;
single.erase(j), single.erase(love[j]);
i += 2;
}
}
for(; i < n; i++){
if(s.empty()) s.push_back(*single.begin());
int u = s.back();
s.pop_back();
active[u] = 0;
single.erase(u);
sol++;
if(active[love[u]]){
i++;
active[love[u]] = 0;
single.erase(love[u]);
if(active[love[love[u]]] && !--deg[love[love[u]]]) s.push_back(love[love[u]]);
if(love[love[u]] == u) sol--;
}
}
cout << sol << "\n";
}
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
204 KB |
Output is correct |
2 |
Correct |
1 ms |
332 KB |
Output is correct |
3 |
Correct |
1 ms |
312 KB |
Output is correct |
4 |
Correct |
1 ms |
204 KB |
Output is correct |
5 |
Correct |
1 ms |
204 KB |
Output is correct |
6 |
Correct |
1 ms |
204 KB |
Output is correct |
7 |
Correct |
1 ms |
204 KB |
Output is correct |
8 |
Correct |
1 ms |
204 KB |
Output is correct |
9 |
Correct |
1 ms |
204 KB |
Output is correct |
10 |
Correct |
1 ms |
316 KB |
Output is correct |
11 |
Correct |
1 ms |
204 KB |
Output is correct |
12 |
Correct |
1 ms |
204 KB |
Output is correct |
13 |
Correct |
1 ms |
204 KB |
Output is correct |
14 |
Correct |
1 ms |
316 KB |
Output is correct |
15 |
Correct |
1 ms |
316 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
204 KB |
Output is correct |
2 |
Correct |
1 ms |
204 KB |
Output is correct |
3 |
Correct |
1 ms |
204 KB |
Output is correct |
4 |
Correct |
361 ms |
16176 KB |
Output is correct |
5 |
Correct |
344 ms |
16124 KB |
Output is correct |
6 |
Correct |
352 ms |
16092 KB |
Output is correct |
7 |
Correct |
1 ms |
332 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
352 ms |
16392 KB |
Output is correct |
2 |
Correct |
360 ms |
16376 KB |
Output is correct |
3 |
Correct |
288 ms |
16060 KB |
Output is correct |
4 |
Correct |
1 ms |
332 KB |
Output is correct |
5 |
Correct |
364 ms |
16204 KB |
Output is correct |
6 |
Correct |
373 ms |
16548 KB |
Output is correct |
7 |
Correct |
326 ms |
16496 KB |
Output is correct |
8 |
Correct |
348 ms |
16544 KB |
Output is correct |
9 |
Correct |
321 ms |
16796 KB |
Output is correct |
10 |
Correct |
261 ms |
16888 KB |
Output is correct |
11 |
Correct |
1 ms |
204 KB |
Output is correct |
12 |
Correct |
1 ms |
204 KB |
Output is correct |
13 |
Correct |
1 ms |
204 KB |
Output is correct |
14 |
Correct |
1 ms |
320 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
204 KB |
Output is correct |
2 |
Correct |
1 ms |
332 KB |
Output is correct |
3 |
Correct |
1 ms |
312 KB |
Output is correct |
4 |
Correct |
1 ms |
204 KB |
Output is correct |
5 |
Correct |
1 ms |
204 KB |
Output is correct |
6 |
Correct |
1 ms |
204 KB |
Output is correct |
7 |
Correct |
1 ms |
204 KB |
Output is correct |
8 |
Correct |
1 ms |
204 KB |
Output is correct |
9 |
Correct |
1 ms |
204 KB |
Output is correct |
10 |
Correct |
1 ms |
316 KB |
Output is correct |
11 |
Correct |
1 ms |
204 KB |
Output is correct |
12 |
Correct |
1 ms |
204 KB |
Output is correct |
13 |
Correct |
1 ms |
204 KB |
Output is correct |
14 |
Correct |
1 ms |
316 KB |
Output is correct |
15 |
Correct |
1 ms |
316 KB |
Output is correct |
16 |
Correct |
1 ms |
204 KB |
Output is correct |
17 |
Correct |
1 ms |
204 KB |
Output is correct |
18 |
Correct |
1 ms |
204 KB |
Output is correct |
19 |
Correct |
361 ms |
16176 KB |
Output is correct |
20 |
Correct |
344 ms |
16124 KB |
Output is correct |
21 |
Correct |
352 ms |
16092 KB |
Output is correct |
22 |
Correct |
1 ms |
332 KB |
Output is correct |
23 |
Correct |
352 ms |
16392 KB |
Output is correct |
24 |
Correct |
360 ms |
16376 KB |
Output is correct |
25 |
Correct |
288 ms |
16060 KB |
Output is correct |
26 |
Correct |
1 ms |
332 KB |
Output is correct |
27 |
Correct |
364 ms |
16204 KB |
Output is correct |
28 |
Correct |
373 ms |
16548 KB |
Output is correct |
29 |
Correct |
326 ms |
16496 KB |
Output is correct |
30 |
Correct |
348 ms |
16544 KB |
Output is correct |
31 |
Correct |
321 ms |
16796 KB |
Output is correct |
32 |
Correct |
261 ms |
16888 KB |
Output is correct |
33 |
Correct |
1 ms |
204 KB |
Output is correct |
34 |
Correct |
1 ms |
204 KB |
Output is correct |
35 |
Correct |
1 ms |
204 KB |
Output is correct |
36 |
Correct |
1 ms |
320 KB |
Output is correct |
37 |
Correct |
391 ms |
16220 KB |
Output is correct |
38 |
Correct |
336 ms |
16480 KB |
Output is correct |
39 |
Correct |
344 ms |
16700 KB |
Output is correct |
40 |
Correct |
380 ms |
16508 KB |
Output is correct |
41 |
Correct |
320 ms |
16552 KB |
Output is correct |
42 |
Correct |
356 ms |
16540 KB |
Output is correct |
43 |
Correct |
332 ms |
16656 KB |
Output is correct |
44 |
Correct |
334 ms |
16552 KB |
Output is correct |
45 |
Correct |
319 ms |
16448 KB |
Output is correct |
46 |
Correct |
314 ms |
16548 KB |
Output is correct |
47 |
Correct |
298 ms |
16932 KB |
Output is correct |
48 |
Correct |
328 ms |
16380 KB |
Output is correct |
49 |
Correct |
343 ms |
16284 KB |
Output is correct |
50 |
Correct |
273 ms |
16128 KB |
Output is correct |
51 |
Correct |
1 ms |
332 KB |
Output is correct |
52 |
Correct |
326 ms |
16100 KB |
Output is correct |
53 |
Correct |
303 ms |
16472 KB |
Output is correct |
54 |
Correct |
311 ms |
16584 KB |
Output is correct |
55 |
Correct |
290 ms |
16452 KB |
Output is correct |
56 |
Correct |
297 ms |
16928 KB |
Output is correct |
57 |
Correct |
240 ms |
16832 KB |
Output is correct |
58 |
Correct |
1 ms |
204 KB |
Output is correct |
59 |
Correct |
1 ms |
204 KB |
Output is correct |
60 |
Correct |
1 ms |
204 KB |
Output is correct |
61 |
Correct |
1 ms |
204 KB |
Output is correct |
62 |
Correct |
1 ms |
204 KB |
Output is correct |
63 |
Correct |
1 ms |
204 KB |
Output is correct |
64 |
Correct |
1 ms |
204 KB |
Output is correct |
65 |
Correct |
336 ms |
16172 KB |
Output is correct |
66 |
Correct |
319 ms |
16036 KB |
Output is correct |
67 |
Correct |
336 ms |
16188 KB |
Output is correct |
68 |
Correct |
1 ms |
332 KB |
Output is correct |
69 |
Correct |
1 ms |
204 KB |
Output is correct |
70 |
Correct |
1 ms |
204 KB |
Output is correct |
71 |
Correct |
1 ms |
204 KB |
Output is correct |
72 |
Correct |
1 ms |
204 KB |
Output is correct |
73 |
Correct |
1 ms |
316 KB |
Output is correct |
74 |
Correct |
1 ms |
204 KB |
Output is correct |
75 |
Correct |
1 ms |
204 KB |
Output is correct |
76 |
Correct |
1 ms |
208 KB |
Output is correct |
77 |
Correct |
1 ms |
204 KB |
Output is correct |
78 |
Correct |
1 ms |
204 KB |
Output is correct |
79 |
Correct |
1 ms |
204 KB |
Output is correct |
80 |
Correct |
1 ms |
204 KB |
Output is correct |
81 |
Correct |
1 ms |
204 KB |
Output is correct |
82 |
Correct |
1 ms |
204 KB |
Output is correct |
83 |
Correct |
1 ms |
204 KB |
Output is correct |