# include <bits/stdc++.h>
using namespace std;
using ll = long long;
using db = long double; // or double, if TL is tight
using str = string; // yay python!
// pairs
using pii = pair<int,int>;
using pl = pair<ll,ll>;
using pd = pair<db,db>;
#define mp make_pair
#define f first
#define s second
#define tcT template<class T
#define tcTU tcT, class U
// ^ lol this makes everything look weird but I'll try it
tcT> using V = vector<T>;
tcT, size_t SZ> using AR = array<T,SZ>;
using vi = V<int>;
using vb = V<bool>;
using vl = V<ll>;
using vd = V<db>;
using vs = V<str>;
using vpi = V<pii>;
using vpl = V<pl>;
using vpd = V<pd>;
// vectors
// oops size(x), rbegin(x), rend(x) need C++17
#define sz(x) int((x).size())
#define bg(x) begin(x)
#define all(x) bg(x), end(x)
#define rall(x) x.rbegin(), x.rend()
#define sor(x) sort(all(x))
#define rsz resize
#define ins insert
#define pb push_back
#define eb emplace_back
#define ft front()
#define bk back()
#define lb lower_bound
#define ub upper_bound
#define FOR(i,a,b) for (int i = (a); i < (b); ++i)
#define F0R(i,a) FOR(i,0,a)
#define ROF(i,a,b) for (int i = (b)-1; i >= (a); --i)
#define R0F(i,a) ROF(i,0,a)
#define rep(a) F0R(_,a)
#define each(a,x) for (auto& a: x)
const int MOD = 998244353;
const int MX = 2e5+5;
const ll BIG = 1e18; // not too close to LLONG_MAX
const db PI = acos((db)-1);
const int dx[4]{1,0,-1,0}, dy[4]{0,1,0,-1}; // for every grid problem!!
mt19937 rng((uint32_t)chrono::steady_clock::now().time_since_epoch().count());
template<class T> using pqg = priority_queue<T,vector<T>,greater<T>>;
struct DSU {
vi e; void init(int N) { e = vi(N,-1); }
int get(int x) { return e[x] < 0 ? x : e[x] = get(e[x]); }
bool sameSet(int a, int b) { return get(a) == get(b); }
int size(int x) { return -e[get(x)]; }
bool unite(int x, int y) { // union by size
x = get(x), y = get(y); if (x == y) return 0;
if (e[x] > e[y]) swap(x,y);
e[x] += e[y]; e[y] = x; return 1;
}
};
const int N = 3e5 + 5, inf = 1e9;
int t,n,a[N],fix[N],par[N],root,special,b[N];
vector <int> v[N];
int dp[N][2][2][2][2];
void dfs(int a, int p) {
fix[a] = 1;
for (int i = 0; i < (int)v[a].size(); i++){
int to = v[a][i];
if (to == p) continue;
if (fix[to]) {
root = a;
special = to;
}
else
dfs(to,a);
}
}
void dfs1(int a, int p) {
par[a] = p;
for (int i = 0; i < (int)v[a].size(); i++) {
int to = v[a][i];
if (to == p) continue;
dfs1(to,a);
}
}
void dfs2(int a, int p, int me, int up, int rt, int sp) {
if (dp[a][me][up][rt][sp] != -1) return ;
if ((a == special && me != sp) || (a == root && me != rt) || (p == root && up != rt) || (p == special && up != sp) || (a == special && up && rt)) {
dp[a][me][up][rt][sp] = inf;
return ;
}
int ff = 0;
if (a != root) {
if(up == 1) ff = 1;
if (a == special && rt) ff = 1;
}
else if (sp) ff = 1;
int dif = 1e9, sum = 0;
for (int i = 0; i < (int)v[a].size(); i++) {
int to = v[a][i];
if (to == p) continue;
dfs2(to,a,0,me,rt,sp);
dfs2(to,a,1,me,rt,sp);
sum += dp[to][0][me][rt][sp];
dif = min(dif, dp[to][1][me][rt][sp] - dp[to][0][me][rt][sp]);
}
dp[a][me][up][rt][sp] = (ff == 1 ? sum + me : sum + dif + me);
}
int main() {
std::ios_base::sync_with_stdio(false),cin.tie(0),cout.tie(0);
cin>>n;
for (int i = 1; i <= n; i++) {
cin>>a[i]>>b[i];
v[a[i]].pb(b[i]);
v[b[i]].pb(a[i]);
}
dfs(1,0);
for (int i = 1; i <= n; i++) v[i].clear();
for (int i = 1; i <= n; i++) {
if (min(a[i],b[i]) == min(root,special) && max(a[i],b[i]) == max(root,special)) {}
else v[a[i]].pb(b[i]), v[b[i]].pb(a[i]);
}
for (int i = 1; i <= n; i++) {
for (int j = 0; j <= 1; j++) {
for (int jj = 0; jj <= 1; jj++) {
for (int ii = 0; ii <= 1; ii++) {
dp[i][j][jj][ii][0] = dp[i][j][jj][ii][1] = -1;
}
}
}
}
int ans = inf;
dfs1(root,0);
for (int rt = 0; rt <= 1; rt++) {
for (int sp = 0; sp <= 1; sp++) {
dfs2(root,0,rt,0,rt,sp);
ans = min(ans,dp[root][rt][0][rt][sp]);
}
}
cout<<(ans > n ? -1 : ans)<<endl;
}
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
5 ms |
7380 KB |
Output is correct |
| 2 |
Correct |
5 ms |
7392 KB |
Output is correct |
| 3 |
Correct |
3 ms |
7380 KB |
Output is correct |
| 4 |
Correct |
3 ms |
7380 KB |
Output is correct |
| 5 |
Correct |
183 ms |
35116 KB |
Output is correct |
| 6 |
Correct |
187 ms |
35148 KB |
Output is correct |
| 7 |
Correct |
228 ms |
35152 KB |
Output is correct |
| 8 |
Correct |
193 ms |
35100 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
4 ms |
7380 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
4 ms |
7380 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
5 ms |
7380 KB |
Output is correct |
| 2 |
Correct |
5 ms |
7392 KB |
Output is correct |
| 3 |
Correct |
3 ms |
7380 KB |
Output is correct |
| 4 |
Correct |
3 ms |
7380 KB |
Output is correct |
| 5 |
Correct |
183 ms |
35116 KB |
Output is correct |
| 6 |
Correct |
187 ms |
35148 KB |
Output is correct |
| 7 |
Correct |
228 ms |
35152 KB |
Output is correct |
| 8 |
Correct |
193 ms |
35100 KB |
Output is correct |
| 9 |
Incorrect |
4 ms |
7380 KB |
Output isn't correct |
| 10 |
Halted |
0 ms |
0 KB |
- |
