#include <bits/stdc++.h>
using namespace std;
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
int n;
cin >> n;
vector<int> to(n);
map<string, int> mp;
for (int i = 0; i < n; i++) {
string s;
cin >> s;
string t;
cin >> t;
if (!mp.count(s)) {
mp[s] = (int) mp.size();
}
if (!mp.count(t)) {
mp[t] = (int) mp.size();
}
to[mp[s]] = mp[t];
}
if (n % 2 == 1) {
cout << -1 << '\n';
return 0;
}
vector<vector<int>> ch(n);
for (int i = 0; i < n; i++) {
if (to[i] == i) {
continue;
}
ch[to[i]].push_back(i);
}
vector<int> deg(n);
for (int i = 0; i < n; i++) {
deg[to[i]] += 1;
}
vector<int> que;
for (int i = 0; i < n; i++) {
if (deg[i] == 0) {
que.push_back(i);
}
}
for (int b = 0; b < (int) que.size(); b++) {
int i = que[b];
deg[to[i]] -= 1;
if (deg[to[i]] == 0) {
que.push_back(to[i]);
}
}
vector<vector<int>> dp(n, vector<int>(2));
vector<int> comp;
function<void(int, int)> Solve = [&](int v, int ban) {
comp.push_back(v);
int mx = 0;
for (int u : ch[v]) {
Solve(u, ban);
dp[v][0] += max(dp[u][0], dp[u][1]);
dp[v][1] += max(dp[u][0], dp[u][1]);
if (u != ban) {
mx = max(mx, -max(dp[u][0], dp[u][1]) + dp[u][0] + 1);
}
}
dp[v][1] += mx;
if (v == ban) {
dp[v][1] = 0;
}
};
int res = 0;
for (int i = 0; i < n; i++) {
if (deg[i] == 0) {
continue;
}
if (to[i] == i) {
Solve(i, -1);
res += max(dp[i][1], dp[i][0]);
} else if (i == to[to[i]]) {
deg[i] = 0;
deg[to[i]] = 0;
{
vector<int> new_ch;
for (int x : ch[i]) {
if (x == to[i]) {
continue;
}
new_ch.push_back(x);
}
ch[i] = new_ch;
}
{
vector<int> new_ch;
for (int x : ch[to[i]]) {
if (x == i) {
continue;
}
new_ch.push_back(x);
}
ch[to[i]] = new_ch;
}
Solve(i, -1);
Solve(to[i], -1);
res += max(max(dp[i][0], dp[i][1]) + max(dp[to[i]][0], dp[to[i]][1]), dp[i][0] + dp[to[i]][0] + 2);
} else {
vector<int> new_ch;
for (int x : ch[to[i]]) {
if (x == i) {
continue;
}
new_ch.push_back(x);
}
ch[to[i]] = new_ch;
int prv = to[i];
to[i] = i;
comp.clear();
Solve(i, -1);
int c = max(dp[i][0], dp[i][1]);
for (int x : comp) {
dp[x][0] = 0;
dp[x][1] = 0;
deg[x] = 0;
}
Solve(i, prv);
c = max(c, dp[i][0] + 1);
res += c;
}
}
cout << (n - 2 * res) + res << '\n';
return 0;
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
344 KB |
Output is correct |
2 |
Correct |
1 ms |
344 KB |
Output is correct |
3 |
Correct |
1 ms |
348 KB |
Output is correct |
4 |
Correct |
1 ms |
348 KB |
Output is correct |
5 |
Correct |
1 ms |
348 KB |
Output is correct |
6 |
Correct |
1 ms |
348 KB |
Output is correct |
7 |
Correct |
1 ms |
348 KB |
Output is correct |
8 |
Correct |
1 ms |
348 KB |
Output is correct |
9 |
Correct |
1 ms |
348 KB |
Output is correct |
10 |
Correct |
1 ms |
348 KB |
Output is correct |
11 |
Correct |
1 ms |
348 KB |
Output is correct |
12 |
Correct |
1 ms |
348 KB |
Output is correct |
13 |
Correct |
1 ms |
348 KB |
Output is correct |
14 |
Correct |
1 ms |
348 KB |
Output is correct |
15 |
Correct |
1 ms |
348 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
348 KB |
Output is correct |
2 |
Correct |
1 ms |
348 KB |
Output is correct |
3 |
Correct |
1 ms |
348 KB |
Output is correct |
4 |
Correct |
216 ms |
32712 KB |
Output is correct |
5 |
Correct |
163 ms |
21960 KB |
Output is correct |
6 |
Correct |
209 ms |
34248 KB |
Output is correct |
7 |
Correct |
133 ms |
10576 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
190 ms |
21776 KB |
Output is correct |
2 |
Correct |
166 ms |
24268 KB |
Output is correct |
3 |
Correct |
137 ms |
18788 KB |
Output is correct |
4 |
Correct |
129 ms |
9860 KB |
Output is correct |
5 |
Correct |
189 ms |
32080 KB |
Output is correct |
6 |
Correct |
157 ms |
20812 KB |
Output is correct |
7 |
Correct |
198 ms |
20768 KB |
Output is correct |
8 |
Correct |
147 ms |
20092 KB |
Output is correct |
9 |
Correct |
151 ms |
20428 KB |
Output is correct |
10 |
Correct |
114 ms |
19540 KB |
Output is correct |
11 |
Correct |
1 ms |
344 KB |
Output is correct |
12 |
Correct |
1 ms |
348 KB |
Output is correct |
13 |
Correct |
1 ms |
348 KB |
Output is correct |
14 |
Correct |
0 ms |
348 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
344 KB |
Output is correct |
2 |
Correct |
1 ms |
344 KB |
Output is correct |
3 |
Correct |
1 ms |
348 KB |
Output is correct |
4 |
Correct |
1 ms |
348 KB |
Output is correct |
5 |
Correct |
1 ms |
348 KB |
Output is correct |
6 |
Correct |
1 ms |
348 KB |
Output is correct |
7 |
Correct |
1 ms |
348 KB |
Output is correct |
8 |
Correct |
1 ms |
348 KB |
Output is correct |
9 |
Correct |
1 ms |
348 KB |
Output is correct |
10 |
Correct |
1 ms |
348 KB |
Output is correct |
11 |
Correct |
1 ms |
348 KB |
Output is correct |
12 |
Correct |
1 ms |
348 KB |
Output is correct |
13 |
Correct |
1 ms |
348 KB |
Output is correct |
14 |
Correct |
1 ms |
348 KB |
Output is correct |
15 |
Correct |
1 ms |
348 KB |
Output is correct |
16 |
Correct |
1 ms |
348 KB |
Output is correct |
17 |
Correct |
1 ms |
348 KB |
Output is correct |
18 |
Correct |
1 ms |
348 KB |
Output is correct |
19 |
Correct |
216 ms |
32712 KB |
Output is correct |
20 |
Correct |
163 ms |
21960 KB |
Output is correct |
21 |
Correct |
209 ms |
34248 KB |
Output is correct |
22 |
Correct |
133 ms |
10576 KB |
Output is correct |
23 |
Correct |
190 ms |
21776 KB |
Output is correct |
24 |
Correct |
166 ms |
24268 KB |
Output is correct |
25 |
Correct |
137 ms |
18788 KB |
Output is correct |
26 |
Correct |
129 ms |
9860 KB |
Output is correct |
27 |
Correct |
189 ms |
32080 KB |
Output is correct |
28 |
Correct |
157 ms |
20812 KB |
Output is correct |
29 |
Correct |
198 ms |
20768 KB |
Output is correct |
30 |
Correct |
147 ms |
20092 KB |
Output is correct |
31 |
Correct |
151 ms |
20428 KB |
Output is correct |
32 |
Correct |
114 ms |
19540 KB |
Output is correct |
33 |
Correct |
1 ms |
344 KB |
Output is correct |
34 |
Correct |
1 ms |
348 KB |
Output is correct |
35 |
Correct |
1 ms |
348 KB |
Output is correct |
36 |
Correct |
0 ms |
348 KB |
Output is correct |
37 |
Correct |
175 ms |
22988 KB |
Output is correct |
38 |
Correct |
198 ms |
23556 KB |
Output is correct |
39 |
Correct |
160 ms |
21004 KB |
Output is correct |
40 |
Correct |
174 ms |
22128 KB |
Output is correct |
41 |
Correct |
175 ms |
21056 KB |
Output is correct |
42 |
Correct |
163 ms |
22604 KB |
Output is correct |
43 |
Correct |
174 ms |
22224 KB |
Output is correct |
44 |
Correct |
200 ms |
22688 KB |
Output is correct |
45 |
Correct |
175 ms |
22608 KB |
Output is correct |
46 |
Correct |
215 ms |
22496 KB |
Output is correct |
47 |
Correct |
181 ms |
21828 KB |
Output is correct |
48 |
Correct |
192 ms |
22400 KB |
Output is correct |
49 |
Correct |
207 ms |
25036 KB |
Output is correct |
50 |
Correct |
154 ms |
19452 KB |
Output is correct |
51 |
Correct |
149 ms |
10576 KB |
Output is correct |
52 |
Correct |
211 ms |
33020 KB |
Output is correct |
53 |
Correct |
198 ms |
21708 KB |
Output is correct |
54 |
Correct |
177 ms |
21648 KB |
Output is correct |
55 |
Correct |
172 ms |
20916 KB |
Output is correct |
56 |
Correct |
175 ms |
21108 KB |
Output is correct |
57 |
Correct |
135 ms |
20372 KB |
Output is correct |
58 |
Correct |
1 ms |
348 KB |
Output is correct |
59 |
Correct |
1 ms |
348 KB |
Output is correct |
60 |
Correct |
1 ms |
348 KB |
Output is correct |
61 |
Correct |
1 ms |
604 KB |
Output is correct |
62 |
Correct |
1 ms |
504 KB |
Output is correct |
63 |
Correct |
1 ms |
344 KB |
Output is correct |
64 |
Correct |
1 ms |
344 KB |
Output is correct |
65 |
Correct |
281 ms |
32716 KB |
Output is correct |
66 |
Correct |
215 ms |
22352 KB |
Output is correct |
67 |
Correct |
232 ms |
34136 KB |
Output is correct |
68 |
Correct |
189 ms |
10800 KB |
Output is correct |
69 |
Correct |
1 ms |
348 KB |
Output is correct |
70 |
Correct |
1 ms |
344 KB |
Output is correct |
71 |
Correct |
1 ms |
344 KB |
Output is correct |
72 |
Correct |
1 ms |
348 KB |
Output is correct |
73 |
Correct |
1 ms |
348 KB |
Output is correct |
74 |
Correct |
1 ms |
348 KB |
Output is correct |
75 |
Correct |
1 ms |
348 KB |
Output is correct |
76 |
Correct |
1 ms |
348 KB |
Output is correct |
77 |
Correct |
1 ms |
348 KB |
Output is correct |
78 |
Correct |
1 ms |
348 KB |
Output is correct |
79 |
Correct |
1 ms |
344 KB |
Output is correct |
80 |
Correct |
1 ms |
348 KB |
Output is correct |
81 |
Correct |
1 ms |
348 KB |
Output is correct |
82 |
Correct |
1 ms |
348 KB |
Output is correct |
83 |
Correct |
1 ms |
348 KB |
Output is correct |