#include<bits/stdc++.h>
using namespace std;
#define endl '\n'
const int N=100005;
map<string,int> m;
vector<int> vis(N);
vector<int> v(N,-1),in(N),inq(N);
inline int id(string s){
if(m.count(s)){
return m[s];
}
int p=m.size();
//cout<<s<<' '<<p<<endl;
m[s]=p;
return p;
}
int32_t main(){
ios_base::sync_with_stdio(false);
cin.tie(0);
int n;cin>>n;
if(n&1){
cout<<-1<<endl;
return 0;
}
for(int i=0;i<n;i++){
string a,b;cin>>a>>b;
v[id(a)]=id(b);
in[id(b)]++;
if(v[id(b)]==id(a)&&a!=b){
vis[id(a)]=vis[id(b)]=1;
}
}
int ans=0;
queue<int> q;
for(int i=0;i<n;i++){
if(in[i]==0){
q.push(i);
}
}
while(q.size()){
int p=q.front();
q.pop();
inq[p]++;
//cout<<p<<endl;
in[v[p]]--;
if(in[v[p]]==0){
q.push(v[p]);
}
if(vis[p]){
continue;
}
ans++;
vis[p]=vis[v[p]]=1;
}
for(int i=0;i<n;i++){
if(vis[i])continue;
int sz=0,f=v[i];
vector<int> a(1,vis[i]);
vis[i]=1;
while(f!=i){
a.push_back(vis[f]);
vis[f]=1;
f=v[f];
}
int idx=0;
for(int i=0;i<a.size();i++){
if(a[i]==0)idx=i;
}
for(int i=0;i<a.size();i++){
//cout<<a[idx]<<endl;
if(a[idx]==0)sz++;
else ans+=(sz+1)/2,sz=0;
idx++;
idx%=(int)a.size();
}
//assert(sz==1);
ans+=(sz+1)/2;
}
cout<<ans<<endl;
return 0;
}
Compilation message
polygon.cpp: In function 'int32_t main()':
polygon.cpp:66:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
66 | for(int i=0;i<a.size();i++){
| ~^~~~~~~~~
polygon.cpp:69:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
69 | for(int i=0;i<a.size();i++){
| ~^~~~~~~~~
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
1884 KB |
Output is correct |
2 |
Correct |
1 ms |
1880 KB |
Output is correct |
3 |
Correct |
1 ms |
1884 KB |
Output is correct |
4 |
Incorrect |
1 ms |
1884 KB |
Output isn't correct |
5 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
1884 KB |
Output is correct |
2 |
Correct |
1 ms |
1884 KB |
Output is correct |
3 |
Correct |
1 ms |
1884 KB |
Output is correct |
4 |
Correct |
234 ms |
10368 KB |
Output is correct |
5 |
Correct |
210 ms |
10068 KB |
Output is correct |
6 |
Correct |
199 ms |
10456 KB |
Output is correct |
7 |
Correct |
1 ms |
1884 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
224 ms |
9860 KB |
Output is correct |
2 |
Correct |
199 ms |
10132 KB |
Output is correct |
3 |
Correct |
175 ms |
9628 KB |
Output is correct |
4 |
Correct |
1 ms |
1880 KB |
Output is correct |
5 |
Correct |
213 ms |
10072 KB |
Output is correct |
6 |
Correct |
193 ms |
9812 KB |
Output is correct |
7 |
Correct |
196 ms |
9812 KB |
Output is correct |
8 |
Correct |
197 ms |
9952 KB |
Output is correct |
9 |
Correct |
185 ms |
10060 KB |
Output is correct |
10 |
Correct |
158 ms |
10068 KB |
Output is correct |
11 |
Correct |
1 ms |
1880 KB |
Output is correct |
12 |
Correct |
1 ms |
1884 KB |
Output is correct |
13 |
Correct |
1 ms |
1884 KB |
Output is correct |
14 |
Correct |
1 ms |
1884 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
1884 KB |
Output is correct |
2 |
Correct |
1 ms |
1880 KB |
Output is correct |
3 |
Correct |
1 ms |
1884 KB |
Output is correct |
4 |
Incorrect |
1 ms |
1884 KB |
Output isn't correct |
5 |
Halted |
0 ms |
0 KB |
- |