#include <bits/stdc++.h>
using namespace std;
#define f1r(i, a, b) for (int i = a; i < b; ++i)
#define f0r(i, a) f1r(i, 0, a)
#define each(t, a) for (auto& t : a)
#define mp make_pair
#define f first
#define s second
#define pb push_back
#define eb emplace_back
#define sz(x) (int)(x).size()
#define all(x) begin(x), end(x)
typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef pair<int, int> pi;
typedef pair<ll, ll> pl;
typedef vector<pi> vpi;
typedef vector<pl> vpl;
template <class T> bool ckmin(T& a, const T& b) { return b < a ? a = b, 1 : 0; }
template <class T> bool ckmax(T& a, const T& b) { return a < b ? a = b, 1 : 0; }
const int INF = numeric_limits<int>::max();
int main() {
cin.tie(0)->sync_with_stdio(0);
int n; cin >> n;
vpi p(n);
f0r(i, n) cin >> p[i].f >> p[i].s;
map<int, vi> X;
map<int, vi> Y;
map<int, vi> S;
map<int, vi> D;
f0r(i, n) {
X[p[i].f].pb(i);
Y[p[i].s].pb(i);
S[p[i].f + p[i].s].pb(i);
D[p[i].f - p[i].s].pb(i);
}
each(v, X) {
sort(all(v.s), [&](int x, int y) {
return p[x].s < p[y].s;
});
}
each(v, Y) {
sort(all(v.s), [&](int x, int y) {
return p[x].f < p[y].f;
});
}
each(v, S) {
sort(all(v.s), [&](int x, int y) {
return p[x].f < p[y].f;
});
}
each(v, D) {
sort(all(v.s), [&](int x, int y) {
return p[x].f < p[y].f;
});
}
auto run_dijkstra = [&](int beg) -> int {
priority_queue<pi, vpi, greater<pi>> pq;
vi dist(4 * n, INF);
vector<bool> vis(4 * n);
int cnt = 0;
pq.push({dist[beg] = 0, beg});
// ad(beg, 0);
auto calc = [&](pi x, pi y) -> int {
int nd = 2 * max(abs(x.f - y.f), abs(x.s - y.s));
if (x.f == y.f) {
nd = abs(x.s - y.s);
} else if (x.s == y.s) {
nd = abs(x.f - y.f);
}
return nd;
};
vi active(n, 1);
while (!pq.empty()) {
auto x = pq.top();
pq.pop();
int u = x.s / 4;
int d = x.s % 4;
if (dist[4 * u + d] < x.f) {
continue;
}
auto ad = [&](int a, ll b) {
if (x.f <= d) return;
cnt++;
if (dist[a] <= b) return;
pq.push({dist[a] = b, a});
};
{ // vertical
auto& v = X[p[u].f];
if (d == 2) {
int loc = 0;
while (v[loc] != u) {
int i = v[loc];
int nd = calc(p[v[loc]], p[u]);
if (nd < x.f) break;
ad(4 * i + 0, nd);
loc++;
}
}
if (d == 0) {
int loc = sz(v) - 1;
while (v[loc] != u) {
int i = v[loc];
int nd = calc(p[v[loc]], p[u]);
if (nd < x.f) break;
ad(4 * i + 2, nd);
loc--;
}
}
}
{ // horizontal
auto& v = Y[p[u].s];
if (d == 3) {
int loc = 0;
while (v[loc] != u) {
int i = v[loc];
int nd = calc(p[v[loc]], p[u]);
if (nd < x.f) break;
ad(4 * i + 1, nd);
loc++;
}
}
if (d == 1) {
int loc = sz(v) - 1;
while (v[loc] != u) {
int i = v[loc];
int nd = calc(p[v[loc]], p[u]);
if (nd < x.f) break;
ad(4 * i + 3, nd);
loc--;
}
}
}
{ // sum
auto& v = S[p[u].f + p[u].s];
if (d == 3) {
int loc = 0;
while (v[loc] != u) {
int i = v[loc];
int nd = calc(p[v[loc]], p[u]);
if (nd < x.f) break;
ad(4 * i + 2, nd);
loc++;
}
}
if (d == 0) {
int loc = 0;
while (v[loc] != u) {
int i = v[loc];
int nd = calc(p[v[loc]], p[u]);
if (nd < x.f) break;
ad(4 * i + 1, nd);
loc++;
}
}
if (d == 1) {
int loc = sz(v) - 1;
while (v[loc] != u) {
int i = v[loc];
int nd = calc(p[v[loc]], p[u]);
if (nd < x.f) break;
ad(4 * i + 0, nd);
loc--;
}
}
if (d == 2) {
int loc = sz(v) - 1;
while (v[loc] != u) {
int i = v[loc];
int nd = calc(p[v[loc]], p[u]);
if (nd < x.f) break;
ad(4 * i + 3, nd);
loc--;
}
}
}
{ // diff
auto& v = D[p[u].f - p[u].s];
if (d == 3) {
int loc = 0;
while (v[loc] != u) {
int i = v[loc];
int nd = calc(p[v[loc]], p[u]);
if (nd < x.f) break;
ad(4 * i + 0, nd);
loc++;
}
}
if (d == 2) {
int loc = 0;
while (v[loc] != u) {
int i = v[loc];
int nd = calc(p[v[loc]], p[u]);
if (nd < x.f) break;
ad(4 * i + 1, nd);
loc++;
}
}
if (d == 0) {
int loc = sz(v) - 1;
while (v[loc] != u) {
int i = v[loc];
int nd = calc(p[v[loc]], p[u]);
if (nd < x.f) break;
ad(4 * i + 3, nd);
loc--;
}
}
if (d == 1) {
int loc = sz(v) - 1;
while (v[loc] != u) {
int i = v[loc];
int nd = calc(p[v[loc]], p[u]);
if (nd < x.f) break;
ad(4 * i + 2, nd);
loc--;
}
}
}
}
int res = 0;
f0r(i, n) {
int a = 0;
f0r(d, 4) {
a += (dist[4 * i + d] < INF);
}
assert(a <= 1);
res += a;
}
return res;
};
int ans = 0;
f0r(d, 4) {
ckmax(ans, run_dijkstra(d));
}
cout << ans << '\n';
return 0;
}
/**
* first try n^2 bash
* 0 - up
* 1 - right
* 2 - down
* 3 - left
*/
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1 ms |
312 KB |
Output is correct |
| 2 |
Correct |
1 ms |
204 KB |
Output is correct |
| 3 |
Incorrect |
1 ms |
204 KB |
Output isn't correct |
| 4 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1 ms |
312 KB |
Output is correct |
| 2 |
Correct |
1 ms |
204 KB |
Output is correct |
| 3 |
Incorrect |
1 ms |
204 KB |
Output isn't correct |
| 4 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
1 ms |
312 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1 ms |
312 KB |
Output is correct |
| 2 |
Correct |
1 ms |
204 KB |
Output is correct |
| 3 |
Incorrect |
1 ms |
204 KB |
Output isn't correct |
| 4 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1 ms |
312 KB |
Output is correct |
| 2 |
Correct |
1 ms |
204 KB |
Output is correct |
| 3 |
Incorrect |
1 ms |
204 KB |
Output isn't correct |
| 4 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1 ms |
312 KB |
Output is correct |
| 2 |
Correct |
1 ms |
204 KB |
Output is correct |
| 3 |
Incorrect |
1 ms |
204 KB |
Output isn't correct |
| 4 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1 ms |
312 KB |
Output is correct |
| 2 |
Correct |
1 ms |
204 KB |
Output is correct |
| 3 |
Incorrect |
1 ms |
204 KB |
Output isn't correct |
| 4 |
Halted |
0 ms |
0 KB |
- |
