///////////////////////////////////////////////////////////////////////////////////////////////
#include <bits/stdc++.h>
using namespace std;
#define mp make_pair
#define pb push_back
#define FAST_IO ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0)
#define FILE_IO(x) freopen((string(x) + ".in").c_str(), "r", stdin); freopen((string(x) + ".out").c_str(), "w", stdout)
#define f first
#define s second
#define x1 x1qwer
#define y1 y1qwer
#define right right123
#define left left123
#define foreach(it, v) for (auto it : v)
#define rep(it, n) for (int it = 0; it < n; ++it)
#define forin(it, l, r) for (int it = l; it < r; ++it)
#define all(x) x.begin(), x.end()
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
const double DINF = numeric_limits<double>::infinity();
const ll MOD = 1e9 + 7;
const double EPS = 1e-7;
ll gcd(ll a, ll b) { return b ? gcd(b, a % b) : a; }
mt19937 mmtw_(MOD);
uniform_int_distribution<ll> rd_;
ll randomll() { return rd_(mmtw_);}
ll rnd(ll x, ll y) { return rd_(mmtw_) % (y - x + 1) + x; }
////////////////////////////////////////////////////////////////////////////////////////////////
struct pt {
int x, y;
int id;
};
inline bool operator==(const pt &a, const pt &b) {
return a.x == b.x && a.y == b.y;
}
inline pt operator-(const pt &a) {
return {-a.x, -a.y};
}
inline pt operator-(const pt &a, const pt &b) {
return {a.x - b.x, a.y - b.y};
}
inline ll dot(const pt &a, const pt &b) {
return 1LL * a.x * b.x + 1LL * a.y * b.y;
}
inline ll cross(const pt &a, const pt &b) {
return 1LL * a.x * b.y - 1LL * a.y * b.x;
}
inline ll dd0(const pt &a) {
return dot(a, a);
}
const int MAXN = 1e5 + 5;
int n;
pt a[MAXN];
bool used[MAXN];
int ord[MAXN];
inline int md(int x) {
if (x >= n) return x - n;
if (x < 0) return x + n;
return x;
}
int findLowest() {
int s = 0;
for (int i = 0; i < n; ++i) {
ll cr = cross(a[i], a[s] - a[i]);
if (cr > 0 || (cr == 0 && dd0(a[i]) < dd0(a[s]))) {
s = i;
}
}
return s;
}
int findHighest() {
int t = 0;
for (int i = 0; i < n; ++i) {
ll cr = cross(a[i], a[t] - a[i]);
if (cr < 0 || (cr == 0 && dd0(a[i]) < dd0(a[t]))) {
t = i;
}
}
return t;
}
struct cmp {
bool operator()(int i, int j) {
if (cross(a[i], a[j]) <= 0) {
return cross(a[j + 1] - a[j], a[i] - a[j]) > 0;
} else {
return cross(a[i + 1] - a[i], a[j] - a[i]) < 0;
}
}
};
int main() {
FAST_IO;
cin >> n;
rep(i, n) {
cin >> a[i].x >> a[i].y;
a[i].id = i + 1;
}
assert(n > 2);
int lowest = findLowest();
if (cross(a[md(lowest - 1)] - a[lowest], a[md(lowest + 1)] - a[lowest]) < 0) {
reverse(a, a + n);
}
rotate(a, a + findLowest(), a + n);
n = findHighest() + 1;
for (int i = 0; i < n; ++i) {
ord[i] = i;
}
sort(ord, ord + n, [](int i, int j){
int cr = cross(a[i], a[j]);
if (cr != 0) return cr > 0;
return dd0(a[i]) < dd0(a[j]);
});
vector<int> res;
set<int, cmp> s;
for (int ii = 0; ii < n; ++ii) {
int i = ord[ii];
bool add = (i + 1 < n && cross(a[i], a[i + 1] - a[i]) > 0);
if (used[i]) {
s.erase(i - 1);
}
if (!s.empty()) {
int f = *s.begin();
if (cross(a[f + 1] - a[f], a[i] - a[f]) > 0) res.push_back(a[i].id);
} else {
res.push_back(a[i].id);
}
if (add) {
s.insert(i);
used[i + 1] = true;
}
}
sort(all(res));
cout << res.size() << '\n';
for (auto it : res) {
cout << it << ' ';
}
cout << '\n';
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
2 ms |
376 KB |
Output is correct |
2 |
Correct |
2 ms |
504 KB |
Output is correct |
3 |
Correct |
3 ms |
504 KB |
Output is correct |
4 |
Correct |
3 ms |
504 KB |
Output is correct |
5 |
Incorrect |
7 ms |
632 KB |
Output isn't correct |
6 |
Incorrect |
7 ms |
632 KB |
Output isn't correct |
7 |
Incorrect |
12 ms |
1016 KB |
Output isn't correct |
8 |
Incorrect |
5 ms |
632 KB |
Output isn't correct |
9 |
Correct |
6 ms |
636 KB |
Output is correct |
10 |
Incorrect |
8 ms |
632 KB |
Output isn't correct |
11 |
Incorrect |
7 ms |
760 KB |
Output isn't correct |
12 |
Correct |
8 ms |
632 KB |
Output is correct |
13 |
Incorrect |
18 ms |
1144 KB |
Output isn't correct |
14 |
Correct |
14 ms |
888 KB |
Output is correct |
15 |
Correct |
18 ms |
1144 KB |
Output is correct |
16 |
Incorrect |
35 ms |
1912 KB |
Output isn't correct |
17 |
Incorrect |
53 ms |
2680 KB |
Output isn't correct |
18 |
Runtime error |
20 ms |
2936 KB |
Execution killed with signal 11 (could be triggered by violating memory limits) |
19 |
Runtime error |
20 ms |
2808 KB |
Execution killed with signal 11 (could be triggered by violating memory limits) |
20 |
Runtime error |
22 ms |
2808 KB |
Execution killed with signal 11 (could be triggered by violating memory limits) |