#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define name "main"
const int N=(int)1e6;
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);
}
map<string,int> mp;
int cn=0;
for(int i=1;i<=n;++i){
string s1,s2; cin>>s1>>s2;
if (mp.find(s1)==mp.end()) mp[s1]=++cn;
if (mp.find(s2)==mp.end()) mp[s2]=++cn;
u[i]=mp[s1];
v[i]=mp[s2];
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);
if (bag[i].size()==2) ans+=2; else ans+=bag[i].size()/2;
if (bag[i].size()%2==0) ans+=dp[i][1]-1; else ans+=dp[i][0];
}
}
cout<<n-ans;
exit(0);
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
21 ms |
124508 KB |
Output is correct |
2 |
Correct |
22 ms |
124496 KB |
Output is correct |
3 |
Correct |
21 ms |
124496 KB |
Output is correct |
4 |
Correct |
21 ms |
124496 KB |
Output is correct |
5 |
Correct |
19 ms |
114124 KB |
Output is correct |
6 |
Correct |
19 ms |
114000 KB |
Output is correct |
7 |
Correct |
21 ms |
122448 KB |
Output is correct |
8 |
Correct |
20 ms |
124504 KB |
Output is correct |
9 |
Correct |
19 ms |
124664 KB |
Output is correct |
10 |
Correct |
22 ms |
124496 KB |
Output is correct |
11 |
Correct |
21 ms |
124496 KB |
Output is correct |
12 |
Correct |
20 ms |
124512 KB |
Output is correct |
13 |
Correct |
22 ms |
124496 KB |
Output is correct |
14 |
Correct |
20 ms |
124496 KB |
Output is correct |
15 |
Correct |
21 ms |
124496 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
20 ms |
122372 KB |
Output is correct |
2 |
Correct |
20 ms |
122448 KB |
Output is correct |
3 |
Correct |
20 ms |
122388 KB |
Output is correct |
4 |
Correct |
162 ms |
139000 KB |
Output is correct |
5 |
Correct |
162 ms |
132040 KB |
Output is correct |
6 |
Correct |
163 ms |
139916 KB |
Output is correct |
7 |
Correct |
19 ms |
114000 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
170 ms |
140616 KB |
Output is correct |
2 |
Correct |
171 ms |
142408 KB |
Output is correct |
3 |
Correct |
149 ms |
136208 KB |
Output is correct |
4 |
Correct |
20 ms |
114000 KB |
Output is correct |
5 |
Correct |
173 ms |
145920 KB |
Output is correct |
6 |
Correct |
172 ms |
139848 KB |
Output is correct |
7 |
Correct |
166 ms |
139848 KB |
Output is correct |
8 |
Correct |
161 ms |
139428 KB |
Output is correct |
9 |
Correct |
157 ms |
139496 KB |
Output is correct |
10 |
Correct |
125 ms |
138696 KB |
Output is correct |
11 |
Correct |
21 ms |
124496 KB |
Output is correct |
12 |
Correct |
20 ms |
124508 KB |
Output is correct |
13 |
Correct |
21 ms |
124496 KB |
Output is correct |
14 |
Correct |
22 ms |
124496 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
21 ms |
124508 KB |
Output is correct |
2 |
Correct |
22 ms |
124496 KB |
Output is correct |
3 |
Correct |
21 ms |
124496 KB |
Output is correct |
4 |
Correct |
21 ms |
124496 KB |
Output is correct |
5 |
Correct |
19 ms |
114124 KB |
Output is correct |
6 |
Correct |
19 ms |
114000 KB |
Output is correct |
7 |
Correct |
21 ms |
122448 KB |
Output is correct |
8 |
Correct |
20 ms |
124504 KB |
Output is correct |
9 |
Correct |
19 ms |
124664 KB |
Output is correct |
10 |
Correct |
22 ms |
124496 KB |
Output is correct |
11 |
Correct |
21 ms |
124496 KB |
Output is correct |
12 |
Correct |
20 ms |
124512 KB |
Output is correct |
13 |
Correct |
22 ms |
124496 KB |
Output is correct |
14 |
Correct |
20 ms |
124496 KB |
Output is correct |
15 |
Correct |
21 ms |
124496 KB |
Output is correct |
16 |
Correct |
20 ms |
122372 KB |
Output is correct |
17 |
Correct |
20 ms |
122448 KB |
Output is correct |
18 |
Correct |
20 ms |
122388 KB |
Output is correct |
19 |
Correct |
162 ms |
139000 KB |
Output is correct |
20 |
Correct |
162 ms |
132040 KB |
Output is correct |
21 |
Correct |
163 ms |
139916 KB |
Output is correct |
22 |
Correct |
19 ms |
114000 KB |
Output is correct |
23 |
Correct |
170 ms |
140616 KB |
Output is correct |
24 |
Correct |
171 ms |
142408 KB |
Output is correct |
25 |
Correct |
149 ms |
136208 KB |
Output is correct |
26 |
Correct |
20 ms |
114000 KB |
Output is correct |
27 |
Correct |
173 ms |
145920 KB |
Output is correct |
28 |
Correct |
172 ms |
139848 KB |
Output is correct |
29 |
Correct |
166 ms |
139848 KB |
Output is correct |
30 |
Correct |
161 ms |
139428 KB |
Output is correct |
31 |
Correct |
157 ms |
139496 KB |
Output is correct |
32 |
Correct |
125 ms |
138696 KB |
Output is correct |
33 |
Correct |
21 ms |
124496 KB |
Output is correct |
34 |
Correct |
20 ms |
124508 KB |
Output is correct |
35 |
Correct |
21 ms |
124496 KB |
Output is correct |
36 |
Correct |
22 ms |
124496 KB |
Output is correct |
37 |
Incorrect |
169 ms |
141148 KB |
Output isn't correct |
38 |
Halted |
0 ms |
0 KB |
- |