#ifdef LOCAL
#define _GLIBCXX_DEBUG
#endif
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;
#define pll pair<ll, ll>
#define pii pair<int, int>
#define pdd pair<ld, ld>
#define ff first
#define ss second
#define all(v) v.begin(),v.end()
typedef tree<
int,
null_type,
less<int>,
rb_tree_tag,
tree_order_statistics_node_update> ordset;
#pragma GCC optimize("-O3")
#pragma GCC optimize("unroll-loops")
#pragma GCC optimize("-Os")
ll INF = 2e18;
ll mod = 1e9 + 7;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
ll binpow(ll n, ll m){
if(m == 0) return 1ll;
if(m & 1ll) return n * binpow(n, m / 2ll);
ll b = binpow(n, m / 2ll);
return b*b;
}
vector<vector<int>> a;
vector<int> dp, dpmark;
void dfs(int v, int p){
int sum = 0;
//cout << v << ' ' << p << '\n';
for(int u : a[v]){
if(u == p) continue;
dfs(u, v);
sum += max(dp[u], dpmark[u]);
}
dp[v] = sum;
for(int u : a[v]){
if(u == p) continue;
dpmark[v] = max(dpmark[v], sum - max(dp[u], dpmark[u]) + dp[u] + 1);
}
}
void solve(){
int n;
cin >> n;
if(n & 1){
cout << -1;
return;
}
map<string, int> names;
vector<int> to(n);
int cur = 0;
for(int i = 0; i < n; i++){
string s, t;
cin >> s >> t;
if(names.find(s) == names.end()) names[s] = cur++;
if(names.find(t) == names.end()) names[t] = cur++;
to[names[s]] = names[t];
}
int cnt = n;
for(int i = 0; i < n; i++){
if(to[i] != -1 && to[i] != i && to[to[i]] == i){
cnt -= 2;
to[to[i]] = -1;
to[i] = -1;
}
}
a.resize(n);
dp.resize(n, 0);
dpmark.resize(n, 0);
int st = -1;
for(int i = 0; i < n; i++){
if(to[i] != -1){
st = i;
a[i].push_back(to[i]);
a[to[i]].push_back(i);
}
}
//cout << st << '\n';
if(st != -1) dfs(st, -1);
cout << max(dpmark[st], dp[st]) + (cnt - max(dpmark[st], dp[st]))*2;
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
#ifdef LOCAL
freopen("input.txt", "r", stdin);
//freopen("output.txt", "w", stdout);
#endif
int tt;
//cin >> tt;
tt = 1;
while (tt--) {
solve();
//solve();
#ifdef LOCAL
cout << "__________________________________" << endl;
#endif
}
#ifdef LOCAL
cout << "finished in " << clock() * 1.0 / CLOCKS_PER_SEC << "sec" << '\n';
#endif
return 0;
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
0 ms |
212 KB |
Output is correct |
2 |
Incorrect |
1 ms |
212 KB |
Output isn't correct |
3 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Incorrect |
1 ms |
212 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Incorrect |
187 ms |
16980 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
0 ms |
212 KB |
Output is correct |
2 |
Incorrect |
1 ms |
212 KB |
Output isn't correct |
3 |
Halted |
0 ms |
0 KB |
- |