#include <bits/stdc++.h>
using namespace std;
int main(){
int n, ans = 0; cin >> n;
vector<pair<string,string>> in;
vector<int> belove(n), love(n);
map<string,int> M;
queue<int> nobody;
vector<bool> vis(n,false);
if(n & 1){
cout << "-1\n"; return 0;
}
for(int i = 0; i < n; ++i){
string s1, s2; cin >> s1 >> s2;
M[s1] = i;
in.push_back({s1,s2});
}
for(int i = 0; i < n; ++i){
love[M[in[i].first]] = M[in[i].second];
belove[M[in[i].second]]++;
}
for(int i = 0; i < n; ++i){
if(love[love[i]] == i && love[i] != i)vis[i] = true;
if(!belove[i]){nobody.push(i);}
}
while(!nobody.empty()){
auto x = nobody.front();
nobody.pop();
vis[x] = true;
if(!vis[love[x]]){
vis[love[x]] = true;
if(--belove[love[love[x]]] == 0)nobody.push(love[love[x]]);
}
ans++;
}
for(int i = 0; i < n; ++i){
if(!vis[i]){
vis[i] = true;
int last = i;
vis[last] = true;
int cnt = 2;
while(love[last] != i){
cnt++;
last = love[last];
vis[last] = true;
}
ans+=(cnt+1)>>1;
}
}
cout << ans << "\n";
}
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
1 ms |
384 KB |
Output is correct |
| 2 |
Correct |
1 ms |
256 KB |
Output is correct |
| 3 |
Correct |
1 ms |
256 KB |
Output is correct |
| 4 |
Correct |
0 ms |
256 KB |
Output is correct |
| 5 |
Correct |
1 ms |
256 KB |
Output is correct |
| 6 |
Correct |
0 ms |
256 KB |
Output is correct |
| 7 |
Correct |
1 ms |
256 KB |
Output is correct |
| 8 |
Correct |
1 ms |
384 KB |
Output is correct |
| 9 |
Correct |
1 ms |
384 KB |
Output is correct |
| 10 |
Correct |
1 ms |
256 KB |
Output is correct |
| 11 |
Correct |
0 ms |
384 KB |
Output is correct |
| 12 |
Correct |
1 ms |
256 KB |
Output is correct |
| 13 |
Correct |
1 ms |
256 KB |
Output is correct |
| 14 |
Correct |
1 ms |
256 KB |
Output is correct |
| 15 |
Correct |
0 ms |
256 KB |
Output is correct |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
1 ms |
256 KB |
Output is correct |
| 2 |
Correct |
0 ms |
256 KB |
Output is correct |
| 3 |
Incorrect |
0 ms |
256 KB |
Output isn't correct |
| 4 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
383 ms |
15516 KB |
Output is correct |
| 2 |
Correct |
380 ms |
17468 KB |
Output is correct |
| 3 |
Correct |
342 ms |
17492 KB |
Output is correct |
| 4 |
Correct |
1 ms |
1152 KB |
Output is correct |
| 5 |
Correct |
380 ms |
17568 KB |
Output is correct |
| 6 |
Correct |
381 ms |
17620 KB |
Output is correct |
| 7 |
Correct |
405 ms |
17620 KB |
Output is correct |
| 8 |
Correct |
364 ms |
17492 KB |
Output is correct |
| 9 |
Correct |
370 ms |
17876 KB |
Output is correct |
| 10 |
Correct |
320 ms |
17888 KB |
Output is correct |
| 11 |
Correct |
1 ms |
256 KB |
Output is correct |
| 12 |
Correct |
0 ms |
256 KB |
Output is correct |
| 13 |
Correct |
1 ms |
256 KB |
Output is correct |
| 14 |
Correct |
1 ms |
256 KB |
Output is correct |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
1 ms |
384 KB |
Output is correct |
| 2 |
Correct |
1 ms |
256 KB |
Output is correct |
| 3 |
Correct |
1 ms |
256 KB |
Output is correct |
| 4 |
Correct |
0 ms |
256 KB |
Output is correct |
| 5 |
Correct |
1 ms |
256 KB |
Output is correct |
| 6 |
Correct |
0 ms |
256 KB |
Output is correct |
| 7 |
Correct |
1 ms |
256 KB |
Output is correct |
| 8 |
Correct |
1 ms |
384 KB |
Output is correct |
| 9 |
Correct |
1 ms |
384 KB |
Output is correct |
| 10 |
Correct |
1 ms |
256 KB |
Output is correct |
| 11 |
Correct |
0 ms |
384 KB |
Output is correct |
| 12 |
Correct |
1 ms |
256 KB |
Output is correct |
| 13 |
Correct |
1 ms |
256 KB |
Output is correct |
| 14 |
Correct |
1 ms |
256 KB |
Output is correct |
| 15 |
Correct |
0 ms |
256 KB |
Output is correct |
| 16 |
Correct |
1 ms |
256 KB |
Output is correct |
| 17 |
Correct |
0 ms |
256 KB |
Output is correct |
| 18 |
Incorrect |
0 ms |
256 KB |
Output isn't correct |
| 19 |
Halted |
0 ms |
0 KB |
- |
