#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define name "main"
const int N=(int)1e5;
vector<string>nen;
string s1[N+2],s2[N+2];
int deg[N+2],num[N+2],low[N+2],id[N+2],scc=0,timedfs=0;
int u[N+2],v[N+2],to[N+2],dp[N+2][2],n;
vector<int>ord,bag[N+2],ke[N+2];
bool used[N+2],del[N+2];
void buildup(int u){
num[u]=low[u]=++timedfs;
ord.push_back(u);
if (!num[to[u]]&&!del[to[u]]){
buildup(to[u]);
low[u]=min(low[u],low[to[u]]);
}
else if (!del[to[u]]) low[u]=min(low[u],num[to[u]]);
if (low[u]==num[u]){
int v;
++scc;
do{
v=ord.back();
ord.pop_back();
id[v]=scc;
del[v]=true;
bag[id[v]].push_back(v);
}while(v!=u);
}
}
void dfs(int u){
if (ke[u].size()==0){
dp[u][0]=0;
dp[u][1]=1;
return;
}
for(auto&v:ke[u]){
dfs(v);
dp[u][1]+=dp[v][0];
}
dp[u][1]++;
for(auto&v:ke[u]){
dp[u][0]=max(dp[u][0],dp[u][1]-1+max(0,dp[v][1]-dp[v][0]));
}
}
int32_t main(){
ios::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
cin>>n;
if (n%2==1){
cout<<-1;
exit(0);
}
for(int i=1;i<=n;++i){
cin>>s1[i]>>s2[i];
nen.push_back(s1[i]);
nen.push_back(s2[i]);
}
sort(nen.begin(),nen.end());
nen.resize(unique(nen.begin(),nen.end())-nen.begin());
for(int i=1;i<=n;++i){
u[i]=upper_bound(nen.begin(),nen.end(),s1[i])-nen.begin();
v[i]=upper_bound(nen.begin(),nen.end(),s2[i])-nen.begin();
to[u[i]]=v[i];
}
for(int i=1;i<=n;++i) if (!num[i]) buildup(i);
for(int i=1;i<=scc;++i){
for(auto&u:bag[i]){
if (id[to[u]]!=i){
ke[id[to[u]]].push_back(i);
deg[i]++;
}
}
}
for(int i=1;i<=scc;++i) {
sort(ke[i].begin(),ke[i].end());
ke[i].resize(unique(ke[i].begin(),ke[i].end())-ke[i].begin());
}
int ans=0;
// for(int i=1;i<=n;++i){
// cout<<u[i]<<' '<<v[i]<<'\n';
// }
// for(int i=1;i<=n;++i) cout<<id[i]<<' '; cout<<'\n';
for(int i=1;i<=scc;++i){
if (deg[i]==0){
dfs(i);
ans+=dp[i][0];
}
}
cout<<n-ans;
exit(0);
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
3 ms |
14928 KB |
Output is correct |
2 |
Correct |
3 ms |
14928 KB |
Output is correct |
3 |
Correct |
4 ms |
14928 KB |
Output is correct |
4 |
Incorrect |
4 ms |
14928 KB |
Output isn't correct |
5 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
3 ms |
14928 KB |
Output is correct |
2 |
Incorrect |
3 ms |
14928 KB |
Output isn't correct |
3 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
120 ms |
30700 KB |
Output is correct |
2 |
Correct |
128 ms |
32688 KB |
Output is correct |
3 |
Correct |
96 ms |
28352 KB |
Output is correct |
4 |
Correct |
3 ms |
12880 KB |
Output is correct |
5 |
Correct |
124 ms |
37232 KB |
Output is correct |
6 |
Correct |
118 ms |
30128 KB |
Output is correct |
7 |
Correct |
120 ms |
30068 KB |
Output is correct |
8 |
Correct |
109 ms |
29556 KB |
Output is correct |
9 |
Correct |
110 ms |
29560 KB |
Output is correct |
10 |
Correct |
91 ms |
29364 KB |
Output is correct |
11 |
Correct |
3 ms |
14928 KB |
Output is correct |
12 |
Correct |
3 ms |
14928 KB |
Output is correct |
13 |
Correct |
3 ms |
14928 KB |
Output is correct |
14 |
Correct |
3 ms |
14928 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
3 ms |
14928 KB |
Output is correct |
2 |
Correct |
3 ms |
14928 KB |
Output is correct |
3 |
Correct |
4 ms |
14928 KB |
Output is correct |
4 |
Incorrect |
4 ms |
14928 KB |
Output isn't correct |
5 |
Halted |
0 ms |
0 KB |
- |