#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";
}
| # |
결과 |
실행 시간 |
메모리 |
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 |
| # |
결과 |
실행 시간 |
메모리 |
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 |
| # |
결과 |
실행 시간 |
메모리 |
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 |
| # |
결과 |
실행 시간 |
메모리 |
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 |
