This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
/*************************************
* author: marvinthang *
* created: 09.07.2023 15:47:28 *
*************************************/
#include <bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define left ___left
#define right ___right
#define TIME (1.0 * clock() / CLOCKS_PER_SEC)
#define MASK(i) (1LL << (i))
#define BIT(x, i) ((x) >> (i) & 1)
#define __builtin_popcount __builtin_popcountll
#define ALL(v) (v).begin(), (v).end()
#define REP(i, n) for (int i = 0, _n = (n); i < _n; ++i)
#define REPD(i, n) for (int i = (n); i--; )
#define FOR(i, a, b) for (int i = (a), _b = (b); i < _b; ++i)
#define FORD(i, b, a) for (int i = (b), _a = (a); --i >= _a; )
#define FORE(i, a, b) for (int i = (a), _b = (b); i <= _b; ++i)
#define FORDE(i, b, a) for (int i = (b), _a = (a); i >= _a; --i)
#define scan_op(...) istream & operator >> (istream &in, __VA_ARGS__ &u)
#define print_op(...) ostream & operator << (ostream &out, const __VA_ARGS__ &u)
#ifdef LOCAL
#include "debug.h"
#else
#define file(name) if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }
#define DB(...) 23
#define db(...) 23
#define debug(...) 23
#endif
template <class U, class V> scan_op(pair <U, V>) { return in >> u.first >> u.second; }
template <class T> scan_op(vector <T>) { for (size_t i = 0; i < u.size(); ++i) in >> u[i]; return in; }
template <class U, class V> print_op(pair <U, V>) { return out << '(' << u.first << ", " << u.second << ')'; }
template <size_t i, class T> ostream & print_tuple_utils(ostream &out, const T &tup) { if constexpr(i == tuple_size<T>::value) return out << ")"; else return print_tuple_utils<i + 1, T>(out << (i ? ", " : "(") << get<i>(tup), tup); }
template <class ...U> print_op(tuple<U...>) { return print_tuple_utils<0, tuple<U...>>(out, u); }
template <class Con, class = decltype(begin(declval<Con>()))> typename enable_if <!is_same<Con, string>::value, ostream&>::type operator << (ostream &out, const Con &con) { out << '{'; for (__typeof(con.begin()) it = con.begin(); it != con.end(); ++it) out << (it == con.begin() ? "" : ", ") << *it; return out << '}'; }
template <class A, class B> bool minimize(A &a, B b) { if (a > b) { a = b; return true; } return false; }
template <class A, class B> bool maximize(A &a, B b) { if (a < b) { a = b; return true; } return false; }
// end of template
const long long INF = 1e18;
const int MAX = 1e5 + 5;
int N, X[MAX], Y[MAX];
void init(void) {
cin >> N;
REP(i, N) cin >> X[i] >> Y[i];
REPD(i, N) X[i] -= X[0], Y[i] -= Y[0];
}
int dir[MAX];
bool inter(int u, int v) {
if (dir[u] == dir[v]) return false;
if ((dir[u] ^ dir[v]) == 2) {
if (BIT(dir[u], 0)) {
if (Y[u] != Y[v]) return false;
return dir[u] == 1 ? X[u] <= X[v] : X[u] >= X[v];
}
if (X[u] != X[v]) return false;
return dir[u] ? Y[u] >= Y[v] : Y[u] <= Y[v];
}
if ((dir[u] ^ dir[v]) == 1) {
if (X[u] + Y[u] != X[v] + Y[v]) return false;
return X[u] > X[v] ? dir[u] == 0 || dir[u] == 3 : dir[v] == 0 || dir[v] == 3;
}
if (X[u] - Y[u] != X[v] - Y[v]) return false;
return X[u] > X[v] ? dir[u] == 2 || dir[u] == 3 : dir[v] == 2 || dir[v] == 3;
}
long long dist[MAX][3];
bool visited[MAX];
vector <int> tadj[MAX][3];
int get_dist(int x, int y) {
return abs(X[x] - X[y]) + abs(Y[x] - Y[y]);
}
void process(void) {
int res = 0;
REP(rt, 4) {
dir[0] = 1;
FOR(i, 1, N) {
if (X[i] >= 0) {
if (Y[i] >= 0) dir[i] = X[i] <= Y[i] ? 2 : 3;
else dir[i] = X[i] <= -Y[i] ? 0 : 3;
} else {
if (Y[i] >= 0) dir[i] = -X[i] < Y[i] ? 2 : 1;
else dir[i] = -X[i] < -Y[i] ? 0 : 1;
}
}
map <int, set <pair <int, int>>> sum[4], diff[4], sx[4], sy[4];
REP(i, N) {
REP(j, 12) {
dist[i][j] = INF;
tadj[i][j].clear();
}
visited[i] = false;
sum[dir[i]][X[i] + Y[i]].emplace(X[i], i);
diff[dir[i]][X[i] - Y[i]].emplace(X[i], i);
sx[dir[i]][X[i]].emplace(Y[i], i);
sy[dir[i]][Y[i]].emplace(X[i], i);
// REP(d, 4) {
// sum[d][X[i] + Y[i]].emplace(-1e9, -1);
// sum[d][X[i] + Y[i]].emplace(1e9, -1);
// diff[d][X[i] - Y[i]].emplace(-1e9, -1);
// diff[d][X[i] - Y[i]].emplace(1e9, -1);
// sx[d][X[i]].emplace(-1e9, -1);
// sx[d][X[i]].emplace(1e9, -1);
// sy[d][Y[i]].emplace(-1e9, -1);
// sy[d][Y[i]].emplace(1e9, -1);
// }
}
REP(i, N) {
int sdir = dir[i] ^ 1;
int ddir = dir[i] ^ 3;
int odir = dir[i] ^ 2;
int s = X[i] + Y[i];
int d = X[i] - Y[i];
auto it = sum[dir[i]][s].find(make_pair(X[i], i));
if (dir[i] == 0 || dir[i] == 3) {
if (next(it) != sum[dir[i]][s].end()) tadj[i][0].push_back(next(it)->se);
} else {
if (it != sum[dir[i]][s].begin()) tadj[i][0].push_back(prev(it)->se);
}
it = diff[dir[i]][d].find(make_pair(X[i], i));
if (dir[i] == 2 || dir[i] == 3) {
if (next(it) != diff[dir[i]][d].end()) tadj[i][1].push_back(next(it)->se);
} else {
if (it != diff[dir[i]][d].begin()) tadj[i][1].push_back(prev(it)->se);
}
if (!BIT(dir[i], 0)) {
it = sx[dir[i]][X[i]].find(make_pair(Y[i], i));
if (dir[i] == 2) {
if (next(it) != sx[dir[i]][X[i]].end()) tadj[i][2].push_back(next(it)->se);
} else {
if (it != sx[dir[i]][X[i]].begin()) tadj[i][2].push_back(prev(it)->se);
}
} else {
it = sy[dir[i]][Y[i]].find(make_pair(X[i], i));
if (dir[i] == 3) {
if (next(it) != sy[dir[i]][Y[i]].end()) tadj[i][2].push_back(next(it)->se);
} else {
if (it != sy[dir[i]][Y[i]].begin()) tadj[i][2].push_back(prev(it)->se);
}
}
}
priority_queue <tuple <long long, int, int>, vector <tuple <long long, int, int>>, greater <tuple <long long, int, int>>> pq;
pq.emplace(0, 0, -1);
int cnt = 0;
while (!pq.empty()) {
auto [du, u, t] = pq.top(); pq.pop();
if (t != -1) {
if (dist[u][t] != du) continue;
for (int v: tadj[u][t]) if (minimize(dist[v][t], du + get_dist(u, v))) pq.emplace(dist[v][t], v, t);
}
if (visited[u]) continue;
visited[u] = true;
vector <pair <int, int>> adj;
int sdir = dir[u] ^ 1;
int ddir = dir[u] ^ 3;
int odir = dir[u] ^ 2;
int s = X[u] + Y[u];
int d = X[u] - Y[u];
sum[dir[u]][X[u] + Y[u]].erase(make_pair(X[u], u));
diff[dir[u]][X[u] - Y[u]].erase(make_pair(X[u], u));
sx[dir[u]][X[u]].erase(make_pair(Y[u], u));
sy[dir[u]][Y[u]].erase(make_pair(X[u], u));
set<pair <int, int>>::iterator it;
if (dir[u] == 0 || dir[u] == 3) {
it = sum[sdir][s].lower_bound(make_pair(X[u] - du / 2, -1));
if (it != sum[sdir][s].begin()) adj.emplace_back(0, prev(it)->se);
} else {
it = sum[sdir][s].lower_bound(make_pair(X[u] + (du + 1) / 2, -1));
if (it != sum[sdir][s].end()) adj.emplace_back(0, it->se);
}
if (dir[u] == 2 || dir[u] == 3) {
it = diff[ddir][d].lower_bound(make_pair(X[u] - du / 2, -1));
if (it != diff[ddir][d].begin()) adj.emplace_back(1, prev(it)->se);
} else {
it = diff[ddir][d].lower_bound(make_pair(X[u] + (du + 1) / 2, -1));
if (it != diff[ddir][d].end()) adj.emplace_back(1, it->se);
}
if (!BIT(dir[u], 0)) {
if (dir[u] == 2) {
it = sx[odir][X[u]].lower_bound(make_pair(Y[u] - du, N));
if (it != sx[odir][X[u]].begin()) adj.emplace_back(2, prev(it)->se);
} else {
it = sx[odir][X[u]].lower_bound(make_pair(Y[u] + du, -1));
if (it != sx[odir][X[u]].end()) adj.emplace_back(2, it->se);
}
} else {
if (dir[u] == 3) {
it = sy[odir][Y[u]].lower_bound(make_pair(X[u] - du, N));
if (it != sy[odir][Y[u]].begin()) adj.emplace_back(2, prev(it)->se);
} else {
it = sy[odir][Y[u]].lower_bound(make_pair(X[u] + du, -1));
if (it != sy[odir][Y[u]].end()) adj.emplace_back(2, it->se);
}
}
for (auto [t, v]: adj) if (minimize(dist[v][t], get_dist(u, v))) pq.emplace(dist[v][t], v, t);
++cnt;
}
maximize(res, cnt);
REP(i, N) {
swap(X[i], Y[i]);
X[i] = -X[i];
}
}
cout << res << '\n';
}
int main(void) {
ios_base::sync_with_stdio(false); cin.tie(nullptr); // cout.tie(nullptr);
file("fever");
init();
process();
cerr << "Time elapsed: " << TIME << " s.\n";
return (0^0);
}
Compilation message (stderr)
fever.cpp: In function 'void process()':
fever.cpp:124:8: warning: unused variable 'sdir' [-Wunused-variable]
124 | int sdir = dir[i] ^ 1;
| ^~~~
fever.cpp:125:8: warning: unused variable 'ddir' [-Wunused-variable]
125 | int ddir = dir[i] ^ 3;
| ^~~~
fever.cpp:126:8: warning: unused variable 'odir' [-Wunused-variable]
126 | int odir = dir[i] ^ 2;
| ^~~~
fever.cpp: In function 'int main()':
fever.cpp:30:61: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
30 | #define file(name) if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
fever.cpp:235:2: note: in expansion of macro 'file'
235 | file("fever");
| ^~~~
fever.cpp:30:94: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
30 | #define file(name) if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
fever.cpp:235:2: note: in expansion of macro 'file'
235 | file("fever");
| ^~~~
fever.cpp: In function 'void process()':
fever.cpp:104:16: warning: iteration 3 invokes undefined behavior [-Waggressive-loop-optimizations]
104 | dist[i][j] = INF;
| ~~~~~~~~~~~^~~~~
fever.cpp:19:58: note: within this loop
19 | #define REP(i, n) for (int i = 0, _n = (n); i < _n; ++i)
| ^
fever.cpp:103:4: note: in expansion of macro 'REP'
103 | REP(j, 12) {
| ^~~
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