/**
* code generated by JHelper
* More info: https://github.com/AlexeyDmitriev/JHelper
* @author Miguel Mini
*/
#include <bits/stdc++.h>
#define sz(x) (int)x.size()
#define trav(v, x) for (auto v : x)
#define re(x, y, z) for (int x=y; x<z; ++x)
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define set_to(x, v) fill(all(x), v)
#define eb emplace_back
#define lso(x) ((x)&-(x))
using namespace std;
using ll = long long;
using ii = pair<int, int>;
using vi = vector<int>;
const int mod = 1e9 + 7;
const int maxn = 2e5 + 10;
vi g[maxn];
int state[maxn];
vi path, cycle;
int m;
void get_cycle(int x, int p) {
state[x] = 1;
path.eb(x);
trav(v, g[x]) {
if (v == p) continue;
if (state[v] == 0) {
get_cycle(v, x);
} else if (state[v] == 1) {
for (int i = sz(path)-1; i >= 0; --i) {
cycle.eb(path[i]);
if (path[i] == v) break;
}
}
}
path.pop_back();
state[x] = 2;
}
using T = pair<int, ll>;
T maxi = {-1, 0};
bool vis[maxn];
T maxLen[maxn];
vector<T> memo[maxn];
T id = {0, 1ll};
void dfs(int x) {
memo[x] = {id};
vis[x] = 1;
trav(v, g[x]) {
if (vis[v]) continue;
dfs(v);
auto q = maxLen[v];
q.first += 1;
memo[x].eb(q);
sort(rall(memo[x]));
int temp_len = memo[x][0].first + memo[x][1].first;
if (temp_len > maxi.first) {
maxi.first = temp_len;
maxi.second = memo[x][0].second * memo[x][1].second;
} else if (temp_len == maxi.first) {
maxi.second += memo[x][0].second * memo[x][1].second;
}
if (memo[x][0].first == memo[x][1].first) {
memo[x][0].second += memo[x][1].second;
}
memo[x].pop_back();
}
maxLen[x] = memo[x][0];
}
T merge(T p, T q) {
if (p.first < q.first) return q;
if (p.first > q.first) return p;
p.second += q.second;
return p;
}
T st[8 * maxn];
int lazy[8 * maxn];
void build(int nx, int l, int r) {
if (l == r) {
st[nx] = maxLen[cycle[r % m]];
st[nx].first += abs(r - (m - 1) / 2);
return;
}
int mid = (l + r) / 2;
build(nx << 1, l, mid);
build(nx << 1 | 1, mid+1, r);
st[nx] = merge(st[nx<<1], st[nx<<1|1]);
}
void unit_upd(int nx, int delta) {
lazy[nx] += delta;
st[nx].first += delta;
}
void push(int nx) {
unit_upd(nx<<1, lazy[nx]);
unit_upd(nx<<1|1, lazy[nx]);
lazy[nx] = 0;
}
void update(int ll, int rr, int delta, int nx, int l, int r) {
if (rr < l or r < ll) return;
if (ll <= l and r <= rr) {
unit_upd(nx, delta);
return;
}
int mid = (l + r) / 2;
push(nx);
update(ll, rr, delta, nx<<1, l, mid);
update(ll, rr, delta, nx<<1|1, mid+1, r);
st[nx] = merge(st[nx<<1], st[nx<<1|1]);
}
T query(int ll, int rr, int nx, int l, int r) {
if (rr < l or r < ll) return {-1, 0};
if (ll <= l and r <= rr) return st[nx];
int mid = (l+r) / 2;
push(nx);
return merge(
query(ll, rr, nx<<1, l, mid),
query(ll, rr, nx<<1|1, mid+1, r)
);
}
class IZHO_14_Shymbulak {
public:
void solveOne(istream& in, ostream& out) {
int n;
in >> n;
re(i, 0, n) {
int a, b;
in >> a >> b;
g[a].eb(b);
g[b].eb(a);
}
get_cycle(1, 0);
trav(v, cycle) vis[v] = 1;
trav(v, cycle) dfs(v);
//trav(v, cycle) {
// out << maxLen[v].first << " " << maxLen[v].second << endl;
//}
//maxi.second *= 2;
//out << maxi.first << " " << maxi.second << endl;
m = sz(cycle);
build(1, 0, 2 * m - 1);
int pos = (m - 1) / 2;
for (int i = 0; i < m; ++i) {
auto L = query(i, pos+i-1, 1, 0, 2 * m - 1);
auto R = query(pos+i+1, m-1+i, 1, 0, 2 * m - 1);
if (L.first < R.first) swap(L, R);
if (L.first == R.first) L.second += R.second;
//if (m % 2 == 0) {
// R = query(m-1+i, m-1+i, 1, 0, 2 * m - 1);
// if (L.first == R.first) L.second += R.second;
//}
auto M = maxLen[cycle[(pos + i) % m]];
int temp = M.first + L.first;
if (temp > maxi.first) {
maxi.first = temp;
maxi.second = M.second * L.second;
} else if (temp == maxi.first) {
maxi.second += M.second * L.second;
}
update(0, pos+i, 1, 1, 0, 2 * m - 1);
update(pos+i+1, 2*m-1, -1, 1, 0, 2 * m - 1);
}
//out << maxi.first << endl;
out << maxi.second << endl;
}
void solve(istream& in, ostream& out) {
int testNumber = 1;
//in >> testNumber;
re(tc, 1, testNumber+1) {
//out << "Case #" << tc << ": ";
solveOne(in, out);
}
}
};
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
IZHO_14_Shymbulak solver;
std::istream& in(std::cin);
std::ostream& out(std::cout);
solver.solve(in, out);
return 0;
}
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
10 ms |
9728 KB |
Output is correct |
| 2 |
Incorrect |
10 ms |
9728 KB |
Output isn't correct |
| 3 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Incorrect |
11 ms |
9984 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
94 ms |
18488 KB |
Output is correct |
| 2 |
Incorrect |
99 ms |
18808 KB |
Output isn't correct |
| 3 |
Halted |
0 ms |
0 KB |
- |
