#include <bits/stdc++.h>
template <class T>
using Vec = std::vector<T>;
int main() {
int N;
std::cin >> N;
if (N % 2 == 1) {
std::cout << -1 << '\n';
return 0;
}
Vec<int> to(N);
{
Vec<std::string> U(N), V(N);
for (int i = 0; i < N; ++i) {
std::cin >> U[i] >> V[i];
}
auto cmp = U;
std::sort(cmp.begin(), cmp.end());
for (int i = 0; i < N; ++i) {
const int u = std::lower_bound(cmp.cbegin(), cmp.cend(), U[i]) - cmp.cbegin();
const int v = std::lower_bound(cmp.cbegin(), cmp.cend(), V[i]) - cmp.cbegin();
to[u] = v;
}
}
Vec<int> deg(N);
for (int i = 0; i < N; ++i) {
deg[to[i]] += 1;
}
Vec<Vec<int>> tree(N);
Vec<bool> used(N);
{
std::queue<int> que;
for (int i = 0; i < N; ++i) {
if (deg[i] == 0) {
que.push(i);
}
}
while (!que.empty()) {
const auto u = que.front();
que.pop();
tree[to[u]].push_back(u);
deg[to[u]] -= 1;
if (deg[to[u]] == 0) {
que.push(to[u]);
}
used[u] = true;
}
}
const auto dfs = [&](auto&& dfs, const int u) -> std::array<int, 2> {
std::array<int, 2> ret{};
int max_dif = 0;
for (const auto v: tree[u]) {
const auto [x, y] = dfs(dfs, v);
ret[0] += std::max(x, y);
max_dif = std::max(max_dif, (x + 1) - std::max(x, y));
}
ret[1] = ret[0] + max_dif;
return ret;
};
int use = 0;
for (int src = 0; src < N; ++src) {
if (used[src]) {
continue;
}
Vec<std::array<int, 2>> val;
{
int u = src;
while (!used[u]) {
val.push_back(dfs(dfs, u));
used[u] = true;
u = to[u];
}
}
const int len = (int) val.size();
if (len == 1) {
use += std::max(val[0][0], val[0][1]);
continue;
}
if (len == 2) {
use += val[0][0] + val[1][0] + 2;
continue;
}
std::array<std::array<int, 2>, 2> dp{};
dp[0][0] = val[0][0];
dp[0][1] = val[0][1];
dp[1][1] = val[0][0] + 1;
for (int i = 1; i < len; ++i) {
std::array<std::array<int, 2>, 2> next{};
for (int j = 0; j < 2; ++j) {
for (int k = 0; k < 2; ++k) {
for (int l = 0; l < 2; ++l) {
for (int m = 0; m < 2; ++m) {
if (j + l + m > 1) {
continue;
}
next[m][k] = std::max(next[m][k], dp[j][k] + val[i][l] + m);
}
}
}
}
dp = std::move(next);
}
use += std::max({ dp[0][0], dp[0][1], dp[1][0] });
}
std::cout << N - use << '\n';
return 0;
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
204 KB |
Output is correct |
2 |
Correct |
1 ms |
296 KB |
Output is correct |
3 |
Correct |
1 ms |
204 KB |
Output is correct |
4 |
Correct |
1 ms |
204 KB |
Output is correct |
5 |
Correct |
1 ms |
204 KB |
Output is correct |
6 |
Correct |
1 ms |
204 KB |
Output is correct |
7 |
Correct |
1 ms |
204 KB |
Output is correct |
8 |
Correct |
1 ms |
204 KB |
Output is correct |
9 |
Correct |
1 ms |
204 KB |
Output is correct |
10 |
Correct |
1 ms |
204 KB |
Output is correct |
11 |
Correct |
1 ms |
292 KB |
Output is correct |
12 |
Correct |
1 ms |
204 KB |
Output is correct |
13 |
Correct |
1 ms |
204 KB |
Output is correct |
14 |
Correct |
1 ms |
204 KB |
Output is correct |
15 |
Correct |
1 ms |
204 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
204 KB |
Output is correct |
2 |
Correct |
1 ms |
204 KB |
Output is correct |
3 |
Correct |
1 ms |
204 KB |
Output is correct |
4 |
Correct |
183 ms |
10084 KB |
Output is correct |
5 |
Correct |
196 ms |
10076 KB |
Output is correct |
6 |
Correct |
191 ms |
10052 KB |
Output is correct |
7 |
Correct |
1 ms |
204 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
195 ms |
10016 KB |
Output is correct |
2 |
Correct |
202 ms |
12228 KB |
Output is correct |
3 |
Correct |
181 ms |
12232 KB |
Output is correct |
4 |
Correct |
1 ms |
204 KB |
Output is correct |
5 |
Correct |
197 ms |
14428 KB |
Output is correct |
6 |
Correct |
196 ms |
12200 KB |
Output is correct |
7 |
Correct |
193 ms |
12176 KB |
Output is correct |
8 |
Correct |
219 ms |
12232 KB |
Output is correct |
9 |
Correct |
233 ms |
12356 KB |
Output is correct |
10 |
Correct |
164 ms |
12184 KB |
Output is correct |
11 |
Correct |
1 ms |
204 KB |
Output is correct |
12 |
Correct |
1 ms |
204 KB |
Output is correct |
13 |
Correct |
1 ms |
204 KB |
Output is correct |
14 |
Correct |
1 ms |
204 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
204 KB |
Output is correct |
2 |
Correct |
1 ms |
296 KB |
Output is correct |
3 |
Correct |
1 ms |
204 KB |
Output is correct |
4 |
Correct |
1 ms |
204 KB |
Output is correct |
5 |
Correct |
1 ms |
204 KB |
Output is correct |
6 |
Correct |
1 ms |
204 KB |
Output is correct |
7 |
Correct |
1 ms |
204 KB |
Output is correct |
8 |
Correct |
1 ms |
204 KB |
Output is correct |
9 |
Correct |
1 ms |
204 KB |
Output is correct |
10 |
Correct |
1 ms |
204 KB |
Output is correct |
11 |
Correct |
1 ms |
292 KB |
Output is correct |
12 |
Correct |
1 ms |
204 KB |
Output is correct |
13 |
Correct |
1 ms |
204 KB |
Output is correct |
14 |
Correct |
1 ms |
204 KB |
Output is correct |
15 |
Correct |
1 ms |
204 KB |
Output is correct |
16 |
Correct |
1 ms |
204 KB |
Output is correct |
17 |
Correct |
1 ms |
204 KB |
Output is correct |
18 |
Correct |
1 ms |
204 KB |
Output is correct |
19 |
Correct |
183 ms |
10084 KB |
Output is correct |
20 |
Correct |
196 ms |
10076 KB |
Output is correct |
21 |
Correct |
191 ms |
10052 KB |
Output is correct |
22 |
Correct |
1 ms |
204 KB |
Output is correct |
23 |
Correct |
195 ms |
10016 KB |
Output is correct |
24 |
Correct |
202 ms |
12228 KB |
Output is correct |
25 |
Correct |
181 ms |
12232 KB |
Output is correct |
26 |
Correct |
1 ms |
204 KB |
Output is correct |
27 |
Correct |
197 ms |
14428 KB |
Output is correct |
28 |
Correct |
196 ms |
12200 KB |
Output is correct |
29 |
Correct |
193 ms |
12176 KB |
Output is correct |
30 |
Correct |
219 ms |
12232 KB |
Output is correct |
31 |
Correct |
233 ms |
12356 KB |
Output is correct |
32 |
Correct |
164 ms |
12184 KB |
Output is correct |
33 |
Correct |
1 ms |
204 KB |
Output is correct |
34 |
Correct |
1 ms |
204 KB |
Output is correct |
35 |
Correct |
1 ms |
204 KB |
Output is correct |
36 |
Correct |
1 ms |
204 KB |
Output is correct |
37 |
Correct |
197 ms |
12184 KB |
Output is correct |
38 |
Correct |
197 ms |
12172 KB |
Output is correct |
39 |
Correct |
199 ms |
12164 KB |
Output is correct |
40 |
Correct |
216 ms |
12192 KB |
Output is correct |
41 |
Correct |
198 ms |
12180 KB |
Output is correct |
42 |
Correct |
231 ms |
12176 KB |
Output is correct |
43 |
Correct |
197 ms |
12232 KB |
Output is correct |
44 |
Correct |
191 ms |
12232 KB |
Output is correct |
45 |
Correct |
232 ms |
12316 KB |
Output is correct |
46 |
Correct |
201 ms |
12228 KB |
Output is correct |
47 |
Correct |
188 ms |
12184 KB |
Output is correct |
48 |
Correct |
202 ms |
12316 KB |
Output is correct |
49 |
Correct |
201 ms |
12192 KB |
Output is correct |
50 |
Correct |
178 ms |
12184 KB |
Output is correct |
51 |
Correct |
1 ms |
208 KB |
Output is correct |
52 |
Correct |
205 ms |
14508 KB |
Output is correct |
53 |
Correct |
198 ms |
12176 KB |
Output is correct |
54 |
Correct |
190 ms |
12184 KB |
Output is correct |
55 |
Correct |
212 ms |
12284 KB |
Output is correct |
56 |
Correct |
186 ms |
12228 KB |
Output is correct |
57 |
Correct |
176 ms |
12228 KB |
Output is correct |
58 |
Correct |
1 ms |
204 KB |
Output is correct |
59 |
Correct |
1 ms |
204 KB |
Output is correct |
60 |
Correct |
1 ms |
204 KB |
Output is correct |
61 |
Correct |
1 ms |
204 KB |
Output is correct |
62 |
Correct |
1 ms |
204 KB |
Output is correct |
63 |
Correct |
1 ms |
204 KB |
Output is correct |
64 |
Correct |
1 ms |
204 KB |
Output is correct |
65 |
Correct |
187 ms |
12228 KB |
Output is correct |
66 |
Correct |
182 ms |
12180 KB |
Output is correct |
67 |
Correct |
183 ms |
12236 KB |
Output is correct |
68 |
Correct |
1 ms |
204 KB |
Output is correct |
69 |
Correct |
1 ms |
204 KB |
Output is correct |
70 |
Correct |
1 ms |
204 KB |
Output is correct |
71 |
Correct |
1 ms |
204 KB |
Output is correct |
72 |
Correct |
1 ms |
204 KB |
Output is correct |
73 |
Correct |
1 ms |
204 KB |
Output is correct |
74 |
Correct |
1 ms |
204 KB |
Output is correct |
75 |
Correct |
1 ms |
204 KB |
Output is correct |
76 |
Correct |
1 ms |
204 KB |
Output is correct |
77 |
Correct |
1 ms |
204 KB |
Output is correct |
78 |
Correct |
1 ms |
204 KB |
Output is correct |
79 |
Correct |
1 ms |
300 KB |
Output is correct |
80 |
Correct |
1 ms |
232 KB |
Output is correct |
81 |
Correct |
1 ms |
204 KB |
Output is correct |
82 |
Correct |
1 ms |
204 KB |
Output is correct |
83 |
Correct |
1 ms |
204 KB |
Output is correct |