#include <bits/stdc++.h>
using namespace std;
#define f first
#define s second
#define pb push_back
#define ar array
#define all(x) x.begin(), x.end()
#define siz(x) (int) x.size()
#define uid(a, b) uniform_int_distribution<int>(a, b)(rng)
#define FOR(i, a, b) for(int i=(a); i<(b); i++)
#define ROF(i, a, b) for(int i=(b-1); i>=(a); i--)
#define F0R(i, n) FOR(i, 0, n)
#define R0F(i, n) ROF(i, 0, n)
#define trav(x, y) for(auto&x:y)
using ll=long long;
using ld=long double;
using pii=pair<int, int>;
using pll=pair<ll, ll>;
using pli=pair<ll, int>;
using vi=vector<int>;
using vl=vector<ll>;
using vpii=vector<pii>;
template<class T> inline bool ckmin(T&a, const T&b) {return b<a?a=b,1:0;}
template<class T> inline bool ckmax(T&a, const T&b) {return b>a?a=b,1:0;}
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
const char nl='\n';
const int mxN=1e5+10;
const int MOD=1e9+7;
const ll infLL=1e18;
const ld eps=1e-6;
int n;
string s[mxN], t[mxN];
unordered_map<string, int> mp;
int a[mxN];
int deg[mxN];
int par[mxN], sz[mxN];
bool alive[mxN];
int used[mxN];
queue<int> q;
int ans=0;
int Find(int u){
return par[u]=(par[u]==u?par[u]:Find(par[u]));
}
bool comb(int e1, int e2){
e1=Find(e1); e2=Find(e2);
if(e1==e2) return 0;
if(sz[e1]<sz[e2]) swap(e1, e2);
sz[e1]+=sz[e2]; sz[e2]=0;
par[e2]=e1;
return 1;
}
int32_t main(){
cin.tie(0)->sync_with_stdio(0);
int n;
cin >> n;
if(n&1) {cout << "-1\n"; return 0;}
F0R(i, n) par[i]=i, sz[i]=1;
F0R(i, n)
cin >> s[i] >> t[i], mp[s[i]]=i;
F0R(i, n){
a[i]=mp[t[i]];
deg[a[i]]++;
alive[i]=1;
}
F0R(i, n){
if(alive[i]&&a[i]!=i&&a[a[i]]==i){
alive[a[i]]=0;
alive[i]=0;
deg[a[i]]--;
deg[i]--;
}
}
F0R(i, n)
if(deg[i]==0){
q.push(i);
}
while(!q.empty()){
auto T=q.front(); q.pop();
assert(deg[T]==0);
if(alive[T]==0) continue;
if(alive[a[T]]==0) continue;
alive[T]=0;
alive[a[T]]=0;
ans++;
if(alive[a[a[T]]]) {
deg[a[a[T]]]--;
if(deg[a[a[T]]]==0)
q.push(a[a[T]]);
}
}
F0R(i, n){
if(alive[i]&&alive[a[i]]){
comb(a[i], i);
}
}
F0R(i, n){
if(alive[i]&&!used[Find(i)]){
used[Find(i)]=1;
ans+=(sz[Find(i)]+1)/2;
}
}
cout << ans << nl;
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
5 ms |
6604 KB |
Output is correct |
2 |
Correct |
4 ms |
6604 KB |
Output is correct |
3 |
Correct |
4 ms |
6604 KB |
Output is correct |
4 |
Correct |
4 ms |
6604 KB |
Output is correct |
5 |
Correct |
4 ms |
6476 KB |
Output is correct |
6 |
Correct |
4 ms |
6476 KB |
Output is correct |
7 |
Correct |
4 ms |
6604 KB |
Output is correct |
8 |
Correct |
4 ms |
6604 KB |
Output is correct |
9 |
Correct |
4 ms |
6604 KB |
Output is correct |
10 |
Correct |
4 ms |
6604 KB |
Output is correct |
11 |
Correct |
4 ms |
6604 KB |
Output is correct |
12 |
Correct |
4 ms |
6604 KB |
Output is correct |
13 |
Correct |
4 ms |
6604 KB |
Output is correct |
14 |
Correct |
4 ms |
6604 KB |
Output is correct |
15 |
Correct |
4 ms |
6604 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
4 ms |
6604 KB |
Output is correct |
2 |
Correct |
4 ms |
6604 KB |
Output is correct |
3 |
Correct |
4 ms |
6604 KB |
Output is correct |
4 |
Correct |
76 ms |
15452 KB |
Output is correct |
5 |
Correct |
75 ms |
15860 KB |
Output is correct |
6 |
Correct |
73 ms |
15420 KB |
Output is correct |
7 |
Correct |
4 ms |
6476 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
78 ms |
16012 KB |
Output is correct |
2 |
Correct |
82 ms |
15848 KB |
Output is correct |
3 |
Correct |
68 ms |
15772 KB |
Output is correct |
4 |
Correct |
4 ms |
6476 KB |
Output is correct |
5 |
Correct |
70 ms |
15464 KB |
Output is correct |
6 |
Correct |
71 ms |
16048 KB |
Output is correct |
7 |
Correct |
72 ms |
16076 KB |
Output is correct |
8 |
Correct |
73 ms |
15960 KB |
Output is correct |
9 |
Correct |
65 ms |
16184 KB |
Output is correct |
10 |
Correct |
56 ms |
15860 KB |
Output is correct |
11 |
Correct |
4 ms |
6604 KB |
Output is correct |
12 |
Correct |
4 ms |
6604 KB |
Output is correct |
13 |
Correct |
4 ms |
6604 KB |
Output is correct |
14 |
Correct |
4 ms |
6604 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
5 ms |
6604 KB |
Output is correct |
2 |
Correct |
4 ms |
6604 KB |
Output is correct |
3 |
Correct |
4 ms |
6604 KB |
Output is correct |
4 |
Correct |
4 ms |
6604 KB |
Output is correct |
5 |
Correct |
4 ms |
6476 KB |
Output is correct |
6 |
Correct |
4 ms |
6476 KB |
Output is correct |
7 |
Correct |
4 ms |
6604 KB |
Output is correct |
8 |
Correct |
4 ms |
6604 KB |
Output is correct |
9 |
Correct |
4 ms |
6604 KB |
Output is correct |
10 |
Correct |
4 ms |
6604 KB |
Output is correct |
11 |
Correct |
4 ms |
6604 KB |
Output is correct |
12 |
Correct |
4 ms |
6604 KB |
Output is correct |
13 |
Correct |
4 ms |
6604 KB |
Output is correct |
14 |
Correct |
4 ms |
6604 KB |
Output is correct |
15 |
Correct |
4 ms |
6604 KB |
Output is correct |
16 |
Correct |
4 ms |
6604 KB |
Output is correct |
17 |
Correct |
4 ms |
6604 KB |
Output is correct |
18 |
Correct |
4 ms |
6604 KB |
Output is correct |
19 |
Correct |
76 ms |
15452 KB |
Output is correct |
20 |
Correct |
75 ms |
15860 KB |
Output is correct |
21 |
Correct |
73 ms |
15420 KB |
Output is correct |
22 |
Correct |
4 ms |
6476 KB |
Output is correct |
23 |
Correct |
78 ms |
16012 KB |
Output is correct |
24 |
Correct |
82 ms |
15848 KB |
Output is correct |
25 |
Correct |
68 ms |
15772 KB |
Output is correct |
26 |
Correct |
4 ms |
6476 KB |
Output is correct |
27 |
Correct |
70 ms |
15464 KB |
Output is correct |
28 |
Correct |
71 ms |
16048 KB |
Output is correct |
29 |
Correct |
72 ms |
16076 KB |
Output is correct |
30 |
Correct |
73 ms |
15960 KB |
Output is correct |
31 |
Correct |
65 ms |
16184 KB |
Output is correct |
32 |
Correct |
56 ms |
15860 KB |
Output is correct |
33 |
Correct |
4 ms |
6604 KB |
Output is correct |
34 |
Correct |
4 ms |
6604 KB |
Output is correct |
35 |
Correct |
4 ms |
6604 KB |
Output is correct |
36 |
Correct |
4 ms |
6604 KB |
Output is correct |
37 |
Correct |
73 ms |
15900 KB |
Output is correct |
38 |
Correct |
79 ms |
16012 KB |
Output is correct |
39 |
Correct |
83 ms |
15952 KB |
Output is correct |
40 |
Correct |
74 ms |
16024 KB |
Output is correct |
41 |
Correct |
70 ms |
16092 KB |
Output is correct |
42 |
Correct |
68 ms |
15972 KB |
Output is correct |
43 |
Correct |
69 ms |
16044 KB |
Output is correct |
44 |
Correct |
71 ms |
16040 KB |
Output is correct |
45 |
Correct |
75 ms |
15980 KB |
Output is correct |
46 |
Correct |
72 ms |
15964 KB |
Output is correct |
47 |
Correct |
68 ms |
16152 KB |
Output is correct |
48 |
Correct |
74 ms |
15976 KB |
Output is correct |
49 |
Correct |
80 ms |
15908 KB |
Output is correct |
50 |
Correct |
67 ms |
15880 KB |
Output is correct |
51 |
Correct |
5 ms |
6592 KB |
Output is correct |
52 |
Correct |
68 ms |
15456 KB |
Output is correct |
53 |
Correct |
69 ms |
16076 KB |
Output is correct |
54 |
Correct |
72 ms |
16040 KB |
Output is correct |
55 |
Correct |
68 ms |
15928 KB |
Output is correct |
56 |
Correct |
70 ms |
16216 KB |
Output is correct |
57 |
Correct |
55 ms |
15876 KB |
Output is correct |
58 |
Correct |
4 ms |
6604 KB |
Output is correct |
59 |
Correct |
4 ms |
6476 KB |
Output is correct |
60 |
Correct |
4 ms |
6604 KB |
Output is correct |
61 |
Correct |
4 ms |
6604 KB |
Output is correct |
62 |
Correct |
4 ms |
6604 KB |
Output is correct |
63 |
Correct |
4 ms |
6476 KB |
Output is correct |
64 |
Correct |
4 ms |
6604 KB |
Output is correct |
65 |
Correct |
80 ms |
15488 KB |
Output is correct |
66 |
Correct |
74 ms |
15852 KB |
Output is correct |
67 |
Correct |
82 ms |
15484 KB |
Output is correct |
68 |
Correct |
4 ms |
6476 KB |
Output is correct |
69 |
Correct |
4 ms |
6604 KB |
Output is correct |
70 |
Correct |
4 ms |
6604 KB |
Output is correct |
71 |
Correct |
4 ms |
6604 KB |
Output is correct |
72 |
Correct |
4 ms |
6604 KB |
Output is correct |
73 |
Correct |
4 ms |
6476 KB |
Output is correct |
74 |
Correct |
4 ms |
6476 KB |
Output is correct |
75 |
Correct |
4 ms |
6604 KB |
Output is correct |
76 |
Correct |
4 ms |
6604 KB |
Output is correct |
77 |
Correct |
4 ms |
6532 KB |
Output is correct |
78 |
Correct |
4 ms |
6604 KB |
Output is correct |
79 |
Correct |
4 ms |
6604 KB |
Output is correct |
80 |
Correct |
4 ms |
6604 KB |
Output is correct |
81 |
Correct |
4 ms |
6604 KB |
Output is correct |
82 |
Correct |
4 ms |
6604 KB |
Output is correct |
83 |
Correct |
4 ms |
6604 KB |
Output is correct |