// author : sentheta aka vanwij
#ifdef VANWIJ
#include"/home/user/code/bits/stdc++.h"
#define DBG 1
#else
#include"bits/stdc++.h"
#define DBG 0
#endif
using namespace std;
#define Int long long
#define V vector
#define pii pair<int,int>
#define ff first
#define ss second
static mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
#define pow2(x) (1LL<<(x))
#define msb(x) (63-__builtin_clzll(x))
#define bitcnt(x) (__builtin_popcountll(x))
#define nl '\n'
#define _ << ' ' <<
#define all(x) (x).begin(), (x).end()
#define rep(i,a,b) for(int i = (int)(a); i < (int)(b); i++)
#define cerr if(DBG) cout
#define dbg(x) {cerr << "?" << #x << " : " << (x) << endl << flush;}
#define int long long
// const Int MOD = 1e9+7;
const Int MOD = 998244353;
Int bpow(Int a,Int b){
Int ret = 1;
for(;b; a=a*a%MOD,b/=2) if(b&1) ret = ret*a%MOD;
return ret;
}
Int inv(Int a){return bpow(a,MOD-2);}
void solve(); int TC, ALLTC;
signed main(){
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0); cout << fixed << setprecision(7);
// cin >> ALLTC; for(TC=1; TC<=ALLTC; TC++) solve(); return 0;
solve();
}
const int N = 1e5+5;
int n;
int out[N];
set<int> in[N];
bool flag[N];
int namecnt = 0;
string names[N];
map<string,int> mp;
void solve(){
cin >> n;
if(n%2){
cout << -1 << nl; return;
}
rep(i,0,n){
string a, b;
cin >> a >> b;
if(!mp.count(a)){
mp[a] = namecnt;
names[namecnt++] = a;
}
if(!mp.count(b)){
mp[b] = namecnt;
names[namecnt++] = b;
}
int u = mp[a], v = mp[b];
out[u] = v;
in[v].insert(u);
cerr << u _ v << nl;
}
// {-indeg, x}
priority_queue<pii> pq;
rep(x,0,n){
if(out[x]!=x && out[out[x]]==x){
flag[x] = 1;
}
else{
pq.push({-in[x].size(), x});
}
}
int ans = 0, fre = 0;
while(!pq.empty()){
auto[deg,x] = pq.top(); pq.pop();
deg *= -1;
if(deg!=(int)in[x].size() || flag[x]) continue;
dbg(x);
if(out[x]!=x && !flag[out[x]]){
flag[x] = flag[out[x]] = 1;
in[out[out[x]]].erase(out[x]);
pq.push({-in[out[out[x]]].size(), out[out[x]]});
out[out[x]] = x;
in[out[x]].erase(x);
ans++;
}
else{
bool found = 0;
for(int y : in[x]){
if(y!=x && !found && !flag[y]){
flag[x] = flag[y] = 1;
out[x] = y;
found = 1;
ans++;
break;
}
}
assert(!found);
if(!found){
fre++;
}
}
dbg(out[x]);
dbg(out[out[x]]);
}
ans += fre;
cout << ans << nl;
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
4 ms |
8148 KB |
Output is correct |
2 |
Correct |
5 ms |
8160 KB |
Output is correct |
3 |
Correct |
4 ms |
8148 KB |
Output is correct |
4 |
Correct |
4 ms |
8148 KB |
Output is correct |
5 |
Correct |
4 ms |
8232 KB |
Output is correct |
6 |
Correct |
5 ms |
8080 KB |
Output is correct |
7 |
Correct |
4 ms |
8148 KB |
Output is correct |
8 |
Correct |
3 ms |
8172 KB |
Output is correct |
9 |
Correct |
3 ms |
8148 KB |
Output is correct |
10 |
Correct |
4 ms |
8148 KB |
Output is correct |
11 |
Correct |
4 ms |
8148 KB |
Output is correct |
12 |
Correct |
3 ms |
8148 KB |
Output is correct |
13 |
Correct |
4 ms |
8148 KB |
Output is correct |
14 |
Correct |
3 ms |
8148 KB |
Output is correct |
15 |
Correct |
4 ms |
8164 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
5 ms |
8148 KB |
Output is correct |
2 |
Correct |
4 ms |
8148 KB |
Output is correct |
3 |
Correct |
4 ms |
8148 KB |
Output is correct |
4 |
Correct |
208 ms |
23588 KB |
Output is correct |
5 |
Correct |
208 ms |
25812 KB |
Output is correct |
6 |
Correct |
247 ms |
25804 KB |
Output is correct |
7 |
Correct |
4 ms |
8148 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
220 ms |
23600 KB |
Output is correct |
2 |
Correct |
219 ms |
25732 KB |
Output is correct |
3 |
Correct |
162 ms |
25720 KB |
Output is correct |
4 |
Correct |
5 ms |
8148 KB |
Output is correct |
5 |
Correct |
229 ms |
25716 KB |
Output is correct |
6 |
Correct |
215 ms |
25688 KB |
Output is correct |
7 |
Correct |
252 ms |
25688 KB |
Output is correct |
8 |
Correct |
217 ms |
25796 KB |
Output is correct |
9 |
Correct |
203 ms |
25768 KB |
Output is correct |
10 |
Correct |
162 ms |
25716 KB |
Output is correct |
11 |
Correct |
4 ms |
8148 KB |
Output is correct |
12 |
Correct |
3 ms |
8164 KB |
Output is correct |
13 |
Correct |
3 ms |
8112 KB |
Output is correct |
14 |
Correct |
4 ms |
8164 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
4 ms |
8148 KB |
Output is correct |
2 |
Correct |
5 ms |
8160 KB |
Output is correct |
3 |
Correct |
4 ms |
8148 KB |
Output is correct |
4 |
Correct |
4 ms |
8148 KB |
Output is correct |
5 |
Correct |
4 ms |
8232 KB |
Output is correct |
6 |
Correct |
5 ms |
8080 KB |
Output is correct |
7 |
Correct |
4 ms |
8148 KB |
Output is correct |
8 |
Correct |
3 ms |
8172 KB |
Output is correct |
9 |
Correct |
3 ms |
8148 KB |
Output is correct |
10 |
Correct |
4 ms |
8148 KB |
Output is correct |
11 |
Correct |
4 ms |
8148 KB |
Output is correct |
12 |
Correct |
3 ms |
8148 KB |
Output is correct |
13 |
Correct |
4 ms |
8148 KB |
Output is correct |
14 |
Correct |
3 ms |
8148 KB |
Output is correct |
15 |
Correct |
4 ms |
8164 KB |
Output is correct |
16 |
Correct |
5 ms |
8148 KB |
Output is correct |
17 |
Correct |
4 ms |
8148 KB |
Output is correct |
18 |
Correct |
4 ms |
8148 KB |
Output is correct |
19 |
Correct |
208 ms |
23588 KB |
Output is correct |
20 |
Correct |
208 ms |
25812 KB |
Output is correct |
21 |
Correct |
247 ms |
25804 KB |
Output is correct |
22 |
Correct |
4 ms |
8148 KB |
Output is correct |
23 |
Correct |
220 ms |
23600 KB |
Output is correct |
24 |
Correct |
219 ms |
25732 KB |
Output is correct |
25 |
Correct |
162 ms |
25720 KB |
Output is correct |
26 |
Correct |
5 ms |
8148 KB |
Output is correct |
27 |
Correct |
229 ms |
25716 KB |
Output is correct |
28 |
Correct |
215 ms |
25688 KB |
Output is correct |
29 |
Correct |
252 ms |
25688 KB |
Output is correct |
30 |
Correct |
217 ms |
25796 KB |
Output is correct |
31 |
Correct |
203 ms |
25768 KB |
Output is correct |
32 |
Correct |
162 ms |
25716 KB |
Output is correct |
33 |
Correct |
4 ms |
8148 KB |
Output is correct |
34 |
Correct |
3 ms |
8164 KB |
Output is correct |
35 |
Correct |
3 ms |
8112 KB |
Output is correct |
36 |
Correct |
4 ms |
8164 KB |
Output is correct |
37 |
Correct |
205 ms |
25708 KB |
Output is correct |
38 |
Correct |
216 ms |
25696 KB |
Output is correct |
39 |
Correct |
222 ms |
25804 KB |
Output is correct |
40 |
Correct |
204 ms |
25752 KB |
Output is correct |
41 |
Correct |
227 ms |
25704 KB |
Output is correct |
42 |
Correct |
223 ms |
25800 KB |
Output is correct |
43 |
Correct |
238 ms |
25776 KB |
Output is correct |
44 |
Correct |
213 ms |
25768 KB |
Output is correct |
45 |
Correct |
230 ms |
25772 KB |
Output is correct |
46 |
Correct |
226 ms |
25780 KB |
Output is correct |
47 |
Correct |
239 ms |
25708 KB |
Output is correct |
48 |
Correct |
210 ms |
25740 KB |
Output is correct |
49 |
Correct |
199 ms |
25760 KB |
Output is correct |
50 |
Correct |
142 ms |
25680 KB |
Output is correct |
51 |
Correct |
3 ms |
8148 KB |
Output is correct |
52 |
Correct |
225 ms |
25964 KB |
Output is correct |
53 |
Correct |
191 ms |
25780 KB |
Output is correct |
54 |
Correct |
191 ms |
25792 KB |
Output is correct |
55 |
Correct |
192 ms |
25856 KB |
Output is correct |
56 |
Correct |
188 ms |
25756 KB |
Output is correct |
57 |
Correct |
144 ms |
25792 KB |
Output is correct |
58 |
Correct |
3 ms |
8148 KB |
Output is correct |
59 |
Correct |
3 ms |
8148 KB |
Output is correct |
60 |
Correct |
3 ms |
8164 KB |
Output is correct |
61 |
Correct |
3 ms |
8148 KB |
Output is correct |
62 |
Correct |
3 ms |
8148 KB |
Output is correct |
63 |
Correct |
5 ms |
8148 KB |
Output is correct |
64 |
Correct |
4 ms |
8164 KB |
Output is correct |
65 |
Correct |
181 ms |
25800 KB |
Output is correct |
66 |
Correct |
190 ms |
25796 KB |
Output is correct |
67 |
Correct |
184 ms |
25688 KB |
Output is correct |
68 |
Correct |
4 ms |
8148 KB |
Output is correct |
69 |
Correct |
3 ms |
8148 KB |
Output is correct |
70 |
Correct |
5 ms |
8300 KB |
Output is correct |
71 |
Correct |
3 ms |
8148 KB |
Output is correct |
72 |
Correct |
3 ms |
8148 KB |
Output is correct |
73 |
Correct |
4 ms |
8172 KB |
Output is correct |
74 |
Correct |
3 ms |
8148 KB |
Output is correct |
75 |
Correct |
3 ms |
8148 KB |
Output is correct |
76 |
Correct |
3 ms |
8168 KB |
Output is correct |
77 |
Correct |
3 ms |
8164 KB |
Output is correct |
78 |
Correct |
4 ms |
8164 KB |
Output is correct |
79 |
Correct |
3 ms |
8148 KB |
Output is correct |
80 |
Correct |
3 ms |
8148 KB |
Output is correct |
81 |
Correct |
4 ms |
8096 KB |
Output is correct |
82 |
Correct |
3 ms |
8148 KB |
Output is correct |
83 |
Correct |
3 ms |
8148 KB |
Output is correct |