#include <bits/stdc++.h>
using namespace std;
#define _ << " _ " <<
#define TRACE(x) cout << #x << " = " << x << endl
#define fi first
#define se second
typedef pair<int, int> pii;
typedef long long ll;
typedef long double ld;
const int MaxN = 1e5 + 10;
int n, x[MaxN], y[MaxN];
pair<int, int> line[MaxN];
ll ccw(int i, int j, int k) {
return (ll)x[i] * (y[j] - y[k]) +
(ll)x[j] * (y[k] - y[i]) +
(ll)x[k] * (y[i] - y[j]);
}
ll dist(int i) {
return (ll)x[i] * x[i] + (ll)y[i] * y[i];
}
bool equ(int i, int j) {
return (ll)y[i] * x[j] == (ll)y[j] * x[i];
}
bool pointCmp(int i, int j) {
if (equ(i, j)) return dist(i) < dist(j);
return (ll)y[i] * x[j] < (ll)y[j] * x[i];
}
bool eventCmp(pair<pii, int>& a, pair<pii, int>& b) {
if (equ(a.fi.fi, b.fi.fi) && a.se != b.se) return a.se < b.se;
return pointCmp(a.fi.fi, b.fi.fi);
}
void printLine(int i) {cout << line[i].fi + 1 << "-" << line[i].se + 1 << " ";}
ld intersec(int i, int j) {
int a = line[j].fi, b = line[j].se;
if (x[a] == x[b]) return x[a];
ld k1 = (ld)y[i] / x[i];
ld k2 = (ld)(y[a] - y[b]) / (x[a] - x[b]);
ld l = (ld)((ll)x[a] * y[b] - (ll)x[b] * y[a]) / (x[a] - x[b]);
if (k1 - k2 == 0) return min(x[a], x[b]);
/*
cout << "intersec " << i + 1 << " ";
printLine(j);
cout << l / (k1 -k2) << endl;
*/
return l / (k1 - k2);
}//*/
bool above(int i, int j) {
// return ccw(line[j].fi, i, line[j].se) > 0;
if (i == line[j].fi || i == line[j].se) return false;
return intersec(i, j) < (ld)x[i];
}
int mod(int i) {
if (i >= n) return i - n;
return i;
}
struct lineCmp {
bool operator()(int i, int j) {
if (i == j) return false;
bool ret;
//cout << line[i].se + 1 << " " << line[j].se + 1 << " " << pointCmp(line[i].se, line[j].se) << endl;
int a1 = line[i].fi, b1 = line[i].se;
int a2 = line[j].fi, b2 = line[j].se;
if ((mod(i + 1) == j))
ret = x[i] < x[mod(i + 2)];
else if ((mod(j + 1) == i))
ret = x[mod(i + 1)] < x[j];
/* else if (pointCmp(line[i].se, line[j].se)) {
cout << "!!!\n";
ret = above(line[j].fi, i);
}
else
ret = above(line[j].se, i);
*/
/* else {
ld min1 = min(intersec(line[j].fi, i), intersec(line[j].se, i));
ld min2 = min(intersec(line[i].fi, j), intersec(line[i].se, j));
ret = min1 < min2;
}
*/
else if (pointCmp(a1, a2) && pointCmp(a2, b1))
ret = above(a2, i);
else if (pointCmp(a1, b2) && pointCmp(b2, b1))
ret = above(b2, i);
else if (pointCmp(a2, a1) && pointCmp(a1, b2))
ret = !above(a1, j);
else if (pointCmp(a2, b1) && pointCmp(b1, b2))
ret = !above(b2, j);
/*
cout << "cmp ";
printLine(i);
printLine(j);
cout << ret << endl << endl;
cin.get();
*/
return ret;
}
};
int main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
cin >> n;
vector<pair<pii, int>> events;
for (int i = 0; i < n; i++) {
cin >> x[i] >> y[i];
events.push_back({{i, i}, 1});
}
for (int i = 0; i < n; i++) {
if (i == n - 1) line[i] = {i, 0};
else line[i] = {i, i + 1};
if (pointCmp(line[i].se, line[i].fi))
swap(line[i].fi, line[i].se);
events.push_back({{line[i].fi, i}, 0});
events.push_back({{line[i].se, i}, 2});
}
// lineCmp c;
//cout << c(6, 8) << endl;
sort(events.begin(), events.end(), eventCmp);
multiset<int, lineCmp> lines;
vector<int> sol;
for (auto ev : events) {
if (ev.se == 0) {
lines.insert(ev.fi.se);
//int l = ev.fi.se;
//cout << "+ ";
//printLine(l);
//cout << endl;
} else if (ev.se == 1) {
int i = ev.fi.se;
// cout << endl;
// TRACE(i + 1);
// for (int l : lines) cout << line[l].fi + 1 << "-" << line[l].se + 1 << " "; cout << endl;
int j = *lines.begin();
// cout << line[j].fi + 1 << "-" << line[j].se + 1 << endl;
// if (intersec(i, j) >= x[i])
if (!above(i, j)) sol.push_back(i);
// if (!above(i, j)) cout << "yes\n";
// cout << endl;
} else {
// cout << "!" << (lines.find(ev.fi.se) != lines.end()) << "!\n";
// cout << lines.size() << " -> ";
lines.erase(ev.fi.se);
// cout << lines.size() << " ";
// cout << "- ";
// printLine(ev.fi.se);
// cout << " " << ev.fi.se << endl;
}
}
sort(sol.begin(), sol.end());
cout << sol.size() << "\n";
for (int i : sol) cout << i + 1 << " ";
return 0;
}
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
2 ms |
376 KB |
Output isn't correct |
| 2 |
Correct |
4 ms |
616 KB |
Output is correct |
| 3 |
Correct |
4 ms |
928 KB |
Output is correct |
| 4 |
Correct |
6 ms |
928 KB |
Output is correct |
| 5 |
Incorrect |
19 ms |
1120 KB |
Output isn't correct |
| 6 |
Incorrect |
21 ms |
1248 KB |
Output isn't correct |
| 7 |
Incorrect |
44 ms |
1740 KB |
Output isn't correct |
| 8 |
Incorrect |
23 ms |
1740 KB |
Output isn't correct |
| 9 |
Incorrect |
19 ms |
1740 KB |
Output isn't correct |
| 10 |
Incorrect |
20 ms |
1740 KB |
Output isn't correct |
| 11 |
Incorrect |
25 ms |
1740 KB |
Output isn't correct |
| 12 |
Correct |
35 ms |
1740 KB |
Output is correct |
| 13 |
Incorrect |
79 ms |
2628 KB |
Output isn't correct |
| 14 |
Correct |
63 ms |
2772 KB |
Output is correct |
| 15 |
Correct |
84 ms |
4436 KB |
Output is correct |
| 16 |
Execution timed out |
155 ms |
8268 KB |
Time limit exceeded |
| 17 |
Execution timed out |
387 ms |
8380 KB |
Time limit exceeded |
| 18 |
Runtime error |
30 ms |
8380 KB |
Execution killed with signal 11 (could be triggered by violating memory limits) |
| 19 |
Runtime error |
34 ms |
8380 KB |
Execution killed with signal 11 (could be triggered by violating memory limits) |
| 20 |
Execution timed out |
288 ms |
8984 KB |
Time limit exceeded |
