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QOJ
ID | Problem | Submitter | Result | Time | Memory | Language | File size | Submit time | Judge time |
---|---|---|---|---|---|---|---|---|---|
#616112 | #9434. Italian Cuisine | XiaoTie | WA | 39ms | 4020kb | C++20 | 33.9kb | 2024-10-05 22:27:15 | 2024-10-05 22:27:15 |
Judging History
answer
#include <bits/stdc++.h>
using namespace std;
using point_t = long double; // 全局数据类型,可修改为 long long 等
constexpr point_t eps = 1e-8;
constexpr long double PI = 3.1415926535897932384l;
int xc, yc, r;
// 点与向量
template <typename T>
struct point {
T x, y;
bool operator==(const point &a) const { return (abs(x - a.x) <= eps && abs(y - a.y) <= eps); }
bool operator<(const point &a) const
{
if (abs(x - a.x) <= eps)
return y < a.y - eps;
return x < a.x - eps;
}
bool operator>(const point &a) const { return !(*this < a || *this == a); }
point operator+(const point &a) const { return {x + a.x, y + a.y}; }
point operator-(const point &a) const { return {x - a.x, y - a.y}; }
point operator-() const { return {-x, -y}; }
point operator*(const T k) const { return {k * x, k * y}; }
point operator/(const T k) const { return {x / k, y / k}; }
T operator*(const point &a) const { return x * a.x + y * a.y; } // 点积
T operator^(const point &a) const { return x * a.y - y * a.x; } // 叉积,注意优先级
int toleft(const point &a) const
{
const auto t = (*this) ^ a;
return (t > eps) - (t < -eps);
} // to-left 测试
T len2() const { return (*this) * (*this); } // 向量长度的平方
T dis2(const point &a) const { return (a - (*this)).len2(); } // 两点距离的平方
// 涉及浮点数
long double len() const { return sqrtl(len2()); } // 向量长度
long double dis(const point &a) const { return sqrtl(dis2(a)); } // 两点距离
long double ang(const point &a) const { return acosl(max(-1.0l, min(1.0l, ((*this) * a) / (len() * a.len())))); } // 向量夹角
point rot(const long double rad) const { return {x * cos(rad) - y * sin(rad), x * sin(rad) + y * cos(rad)}; } // 逆时针旋转(给定角度)
point rot(const long double cosr, const long double sinr) const { return {x * cosr - y * sinr, x * sinr + y * cosr}; } // 逆时针旋转(给定角度的正弦与余弦)
};
using Point = point<point_t>;
// 极角排序
struct argcmp {
bool operator()(const Point &a, const Point &b) const
{
const auto quad = [](const Point &a) {
if (a.y < -eps)
return 1;
if (a.y > eps)
return 4;
if (a.x < -eps)
return 5;
if (a.x > eps)
return 3;
return 2;
};
const int qa = quad(a), qb = quad(b);
if (qa != qb)
return qa < qb;
const auto t = a ^ b;
// if (abs(t)<=eps) return a*a<b*b-eps; // 不同长度的向量需要分开
return t > eps;
}
};
// 直线
template <typename T>
struct line {
point<T> p, v; // p 为直线上一点,v 为方向向量
bool operator==(const line &a) const { return v.toleft(a.v) == 0 && v.toleft(p - a.p) == 0; }
int toleft(const point<T> &a) const { return v.toleft(a - p); } // to-left 测试
bool operator<(const line &a) const // 半平面交算法定义的排序
{
if (abs(v ^ a.v) <= eps && v * a.v >= -eps)
return toleft(a.p) == -1;
return argcmp()(v, a.v);
}
// 涉及浮点数
point<T> inter(const line &a) const { return p + v * ((a.v ^ (p - a.p)) / (v ^ a.v)); } // 直线交点
long double dis(const point<T> &a) const { return abs(v ^ (a - p)) / v.len(); } // 点到直线距离
point<T> proj(const point<T> &a) const { return p + v * ((v * (a - p)) / (v * v)); } // 点在直线上的投影
};
using Line = line<point_t>;
// 线段
template <typename T>
struct segment {
point<T> a, b;
bool operator<(const segment &s) const { return make_pair(a, b) < make_pair(s.a, s.b); }
// 判定性函数建议在整数域使用
// 判断点是否在线段上
// -1 点在线段端点 | 0 点不在线段上 | 1 点严格在线段上
int is_on(const point<T> &p) const
{
if (p == a || p == b)
return -1;
return (p - a).toleft(p - b) == 0 && (p - a) * (p - b) < -eps;
}
// 判断线段直线是否相交
// -1 直线经过线段端点 | 0 线段和直线不相交 | 1 线段和直线严格相交
int is_inter(const line<T> &l) const
{
if (l.toleft(a) == 0 || l.toleft(b) == 0)
return -1;
return l.toleft(a) != l.toleft(b);
}
// 判断两线段是否相交
// -1 在某一线段端点处相交 | 0 两线段不相交 | 1 两线段严格相交
int is_inter(const segment<T> &s) const
{
if (is_on(s.a) || is_on(s.b) || s.is_on(a) || s.is_on(b))
return -1;
const line<T> l{a, b - a}, ls{s.a, s.b - s.a};
return l.toleft(s.a) * l.toleft(s.b) == -1 && ls.toleft(a) * ls.toleft(b) == -1;
}
// 点到线段距离
long double dis(const point<T> &p) const
{
if ((p - a) * (b - a) < -eps || (p - b) * (a - b) < -eps)
return min(p.dis(a), p.dis(b));
const line<T> l{a, b - a};
return l.dis(p);
}
// 两线段间距离
long double dis(const segment<T> &s) const
{
if (is_inter(s))
return 0;
return min({dis(s.a), dis(s.b), s.dis(a), s.dis(b)});
}
};
using Segment = segment<point_t>;
// 多边形
template <typename T>
struct polygon {
vector<point<T>> p; // 以逆时针顺序存储
size_t nxt(const size_t i) const { return i == p.size() - 1 ? 0 : i + 1; }
size_t pre(const size_t i) const { return i == 0 ? p.size() - 1 : i - 1; }
// 回转数
// 返回值第一项表示点是否在多边形边上
// 对于狭义多边形,回转数为 0 表示点在多边形外,否则点在多边形内
pair<bool, int> winding(const point<T> &a) const
{
int cnt = 0;
for (size_t i = 0; i < p.size(); i++) {
const point<T> u = p[i], v = p[nxt(i)];
if (abs((a - u) ^ (a - v)) <= eps && (a - u) * (a - v) <= eps)
return {true, 0};
if (abs(u.y - v.y) <= eps)
continue;
const Line uv = {u, v - u};
if (u.y < v.y - eps && uv.toleft(a) <= 0)
continue;
if (u.y > v.y + eps && uv.toleft(a) >= 0)
continue;
if (u.y < a.y - eps && v.y >= a.y - eps)
cnt++;
if (u.y >= a.y - eps && v.y < a.y - eps)
cnt--;
}
return {false, cnt};
}
// 多边形面积的两倍
// 可用于判断点的存储顺序是顺时针或逆时针
T area() const
{
T sum = 0;
for (size_t i = 0; i < p.size(); i++)
sum += p[i] ^ p[nxt(i)];
return sum;
}
// 多边形的周长
long double circ() const
{
long double sum = 0;
for (size_t i = 0; i < p.size(); i++)
sum += p[i].dis(p[nxt(i)]);
return sum;
}
};
using Polygon = polygon<point_t>;
// 凸多边形
template <typename T>
struct convex : polygon<T> {
// 闵可夫斯基和
convex operator+(const convex &c) const
{
const auto &p = this->p;
vector<Segment> e1(p.size()), e2(c.p.size()), edge(p.size() + c.p.size());
vector<point<T>> res;
res.reserve(p.size() + c.p.size());
const auto cmp = [](const Segment &u, const Segment &v) { return argcmp()(u.b - u.a, v.b - v.a); };
for (size_t i = 0; i < p.size(); i++)
e1[i] = {p[i], p[this->nxt(i)]};
for (size_t i = 0; i < c.p.size(); i++)
e2[i] = {c.p[i], c.p[c.nxt(i)]};
rotate(e1.begin(), min_element(e1.begin(), e1.end(), cmp), e1.end());
rotate(e2.begin(), min_element(e2.begin(), e2.end(), cmp), e2.end());
merge(e1.begin(), e1.end(), e2.begin(), e2.end(), edge.begin(), cmp);
const auto check = [](const vector<point<T>> &res, const point<T> &u) {
const auto back1 = res.back(), back2 = *prev(res.end(), 2);
return (back1 - back2).toleft(u - back1) == 0 && (back1 - back2) * (u - back1) >= -eps;
};
auto u = e1[0].a + e2[0].a;
for (const auto &v : edge) {
while (res.size() > 1 && check(res, u))
res.pop_back();
res.push_back(u);
u = u + v.b - v.a;
}
if (res.size() > 1 && check(res, res[0]))
res.pop_back();
return {res};
}
// 旋转卡壳
// func 为更新答案的函数,可以根据题目调整位置
void rotcaliper(T &ans, T &res) const
{
std::function<void(const point<T> &, const point<T> &, const point<T> &)> funcadd = [&](const point<T> &u, const point<T> &v, const point<T> &w) {
ans += (w - u) ^ (w - v);
};
std::function<void(const point<T> &, const point<T> &, const point<T> &)> funcsub = [&](const point<T> &u, const point<T> &v, const point<T> &w) {
ans -= (w - u) ^ (w - v);
};
std::function<void()> func = [&]() {
res = max(res, ans);
};
const auto &p = this->p;
const auto area = [](const point<T> &u, const point<T> &v, const point<T> &w) { return (w - u) ^ (w - v); };
for (size_t i = 0, j = 1; i < p.size(); i++) {
const auto nxti = this->nxt(i);
while (area(p[this->nxt(j)], p[i], p[nxti]) >= area(p[j], p[i], p[nxti])) {
Line x = {p[i], p[this->nxt(j)] - p[i]};
if (x.dis({xc, yc}) <= r) {
break;
}
int nxtj = this->nxt(j);
funcadd(p[i], p[j], p[nxtj]);
func();
j = nxtj;
}
funcsub(p[i], p[nxti], p[j]);
}
}
// 题目要求的答案
T get_area() const
{
const auto &p = this->p;
if (p.size() == 1)
return 0;
if (p.size() == 2)
return 0;
T ans = 0;
T res = 0;
rotcaliper(ans, res);
return res;
}
// 凸多边形的直径的平方
// T diameter2() const
// {
// const auto &p = this->p;
// if (p.size() == 1)
// return 0;
// if (p.size() == 2)
// return p[0].dis2(p[1]);
// T ans = 0;
// auto func = [&](const point<T> &u, const point<T> &v, const point<T> &w) { ans = max({ans, w.dis2(u), w.dis2(v)}); };
// rotcaliper(func);
// return ans;
// }
// 判断点是否在凸多边形内
// 复杂度 O(logn)
// -1 点在多边形边上 | 0 点在多边形外 | 1 点在多边形内
int is_in(const point<T> &a) const
{
const auto &p = this->p;
if (p.size() == 1)
return a == p[0] ? -1 : 0;
if (p.size() == 2)
return segment<T>{p[0], p[1]}.is_on(a) ? -1 : 0;
if (a == p[0])
return -1;
if ((p[1] - p[0]).toleft(a - p[0]) == -1 || (p.back() - p[0]).toleft(a - p[0]) == 1)
return 0;
const auto cmp = [&](const Point &u, const Point &v) { return (u - p[0]).toleft(v - p[0]) == 1; };
const size_t i = lower_bound(p.begin() + 1, p.end(), a, cmp) - p.begin();
if (i == 1)
return segment<T>{p[0], p[i]}.is_on(a) ? -1 : 0;
if (i == p.size() - 1 && segment<T>{p[0], p[i]}.is_on(a))
return -1;
if (segment<T>{p[i - 1], p[i]}.is_on(a))
return -1;
return (p[i] - p[i - 1]).toleft(a - p[i - 1]) > 0;
}
// 凸多边形关于某一方向的极点
// 复杂度 O(logn)
// 参考资料:https://codeforces.com/blog/entry/48868
template <typename F>
size_t extreme(const F &dir) const
{
const auto &p = this->p;
const auto check = [&](const size_t i) { return dir(p[i]).toleft(p[this->nxt(i)] - p[i]) >= 0; };
const auto dir0 = dir(p[0]);
const auto check0 = check(0);
if (!check0 && check(p.size() - 1))
return 0;
const auto cmp = [&](const Point &v) {
const size_t vi = &v - p.data();
if (vi == 0)
return 1;
const auto checkv = check(vi);
const auto t = dir0.toleft(v - p[0]);
if (vi == 1 && checkv == check0 && t == 0)
return 1;
return checkv ^ (checkv == check0 && t <= 0);
};
return partition_point(p.begin(), p.end(), cmp) - p.begin();
}
// 过凸多边形外一点求凸多边形的切线,返回切点下标
// 复杂度 O(logn)
// 必须保证点在多边形外
pair<size_t, size_t> tangent(const point<T> &a) const
{
const size_t i = extreme([&](const point<T> &u) { return u - a; });
const size_t j = extreme([&](const point<T> &u) { return a - u; });
return {i, j};
}
// 求平行于给定直线的凸多边形的切线,返回切点下标
// 复杂度 O(logn)
pair<size_t, size_t> tangent(const line<T> &a) const
{
const size_t i = extreme([&](...) { return a.v; });
const size_t j = extreme([&](...) { return -a.v; });
return {i, j};
}
};
using Convex = convex<point_t>;
// 圆
struct Circle {
Point c;
long double r;
bool operator==(const Circle &a) const { return c == a.c && abs(r - a.r) <= eps; }
long double circ() const { return 2 * PI * r; } // 周长
long double area() const { return PI * r * r; } // 面积
// 点与圆的关系
// -1 圆上 | 0 圆外 | 1 圆内
int is_in(const Point &p) const
{
const long double d = p.dis(c);
return abs(d - r) <= eps ? -1 : d < r - eps;
}
// 直线与圆关系
// 0 相离 | 1 相切 | 2 相交
int relation(const Line &l) const
{
const long double d = l.dis(c);
if (d > r + eps)
return 0;
if (abs(d - r) <= eps)
return 1;
return 2;
}
// 圆与圆关系
// -1 相同 | 0 相离 | 1 外切 | 2 相交 | 3 内切 | 4 内含
int relation(const Circle &a) const
{
if (*this == a)
return -1;
const long double d = c.dis(a.c);
if (d > r + a.r + eps)
return 0;
if (abs(d - r - a.r) <= eps)
return 1;
if (abs(d - abs(r - a.r)) <= eps)
return 3;
if (d < abs(r - a.r) - eps)
return 4;
return 2;
}
// 直线与圆的交点
vector<Point> inter(const Line &l) const
{
const long double d = l.dis(c);
const Point p = l.proj(c);
const int t = relation(l);
if (t == 0)
return vector<Point>();
if (t == 1)
return vector<Point>{p};
const long double k = sqrt(r * r - d * d);
return vector<Point>{p - (l.v / l.v.len()) * k, p + (l.v / l.v.len()) * k};
}
// 圆与圆交点
vector<Point> inter(const Circle &a) const
{
const long double d = c.dis(a.c);
const int t = relation(a);
if (t == -1 || t == 0 || t == 4)
return vector<Point>();
Point e = a.c - c;
e = e / e.len() * r;
if (t == 1 || t == 3) {
if (r * r + d * d - a.r * a.r >= -eps)
return vector<Point>{c + e};
return vector<Point>{c - e};
}
const long double costh = (r * r + d * d - a.r * a.r) / (2 * r * d), sinth = sqrt(1 - costh * costh);
return vector<Point>{c + e.rot(costh, -sinth), c + e.rot(costh, sinth)};
}
// 圆与圆交面积
long double inter_area(const Circle &a) const
{
const long double d = c.dis(a.c);
const int t = relation(a);
if (t == -1)
return area();
if (t < 2)
return 0;
if (t > 2)
return min(area(), a.area());
const long double costh1 = (r * r + d * d - a.r * a.r) / (2 * r * d), costh2 = (a.r * a.r + d * d - r * r) / (2 * a.r * d);
const long double sinth1 = sqrt(1 - costh1 * costh1), sinth2 = sqrt(1 - costh2 * costh2);
const long double th1 = acos(costh1), th2 = acos(costh2);
return r * r * (th1 - costh1 * sinth1) + a.r * a.r * (th2 - costh2 * sinth2);
}
// 过圆外一点圆的切线
vector<Line> tangent(const Point &a) const
{
const int t = is_in(a);
if (t == 1)
return vector<Line>();
if (t == -1) {
const Point v = {-(a - c).y, (a - c).x};
return vector<Line>{{a, v}};
}
Point e = a - c;
e = e / e.len() * r;
const long double costh = r / c.dis(a), sinth = sqrt(1 - costh * costh);
const Point t1 = c + e.rot(costh, -sinth), t2 = c + e.rot(costh, sinth);
return vector<Line>{{a, t1 - a}, {a, t2 - a}};
}
// 两圆的公切线
vector<Line> tangent(const Circle &a) const
{
const int t = relation(a);
vector<Line> lines;
if (t == -1 || t == 4)
return lines;
if (t == 1 || t == 3) {
const Point p = inter(a)[0], v = {-(a.c - c).y, (a.c - c).x};
lines.push_back({p, v});
}
const long double d = c.dis(a.c);
const Point e = (a.c - c) / (a.c - c).len();
if (t <= 2) {
const long double costh = (r - a.r) / d, sinth = sqrt(1 - costh * costh);
const Point d1 = e.rot(costh, -sinth), d2 = e.rot(costh, sinth);
const Point u1 = c + d1 * r, u2 = c + d2 * r, v1 = a.c + d1 * a.r, v2 = a.c + d2 * a.r;
lines.push_back({u1, v1 - u1});
lines.push_back({u2, v2 - u2});
}
if (t == 0) {
const long double costh = (r + a.r) / d, sinth = sqrt(1 - costh * costh);
const Point d1 = e.rot(costh, -sinth), d2 = e.rot(costh, sinth);
const Point u1 = c + d1 * r, u2 = c + d2 * r, v1 = a.c - d1 * a.r, v2 = a.c - d2 * a.r;
lines.push_back({u1, v1 - u1});
lines.push_back({u2, v2 - u2});
}
return lines;
}
// 圆的反演
tuple<int, Circle, Line> inverse(const Line &l) const
{
const Circle null_c = {{0.0, 0.0}, 0.0};
const Line null_l = {{0.0, 0.0}, {0.0, 0.0}};
if (l.toleft(c) == 0)
return {2, null_c, l};
const Point v = l.toleft(c) == 1 ? Point{l.v.y, -l.v.x} : Point{-l.v.y, l.v.x};
const long double d = r * r / l.dis(c);
const Point p = c + v / v.len() * d;
return {1, {(c + p) / 2, d / 2}, null_l};
}
tuple<int, Circle, Line> inverse(const Circle &a) const
{
const Circle null_c = {{0.0, 0.0}, 0.0};
const Line null_l = {{0.0, 0.0}, {0.0, 0.0}};
const Point v = a.c - c;
if (a.is_in(c) == -1) {
const long double d = r * r / (a.r + a.r);
const Point p = c + v / v.len() * d;
return {2, null_c, {p, {-v.y, v.x}}};
}
if (c == a.c)
return {1, {c, r * r / a.r}, null_l};
const long double d1 = r * r / (c.dis(a.c) - a.r), d2 = r * r / (c.dis(a.c) + a.r);
const Point p = c + v / v.len() * d1, q = c + v / v.len() * d2;
return {1, {(p + q) / 2, p.dis(q) / 2}, null_l};
}
};
// 圆与多边形面积交
long double area_inter(const Circle &circ, const Polygon &poly)
{
const auto cal = [](const Circle &circ, const Point &a, const Point &b) {
if ((a - circ.c).toleft(b - circ.c) == 0)
return 0.0l;
const auto ina = circ.is_in(a), inb = circ.is_in(b);
const Line ab = {a, b - a};
if (ina && inb)
return ((a - circ.c) ^ (b - circ.c)) / 2;
if (ina && !inb) {
const auto t = circ.inter(ab);
const Point p = t.size() == 1 ? t[0] : t[1];
const long double ans = ((a - circ.c) ^ (p - circ.c)) / 2;
const long double th = (p - circ.c).ang(b - circ.c);
const long double d = circ.r * circ.r * th / 2;
if ((a - circ.c).toleft(b - circ.c) == 1)
return ans + d;
return ans - d;
}
if (!ina && inb) {
const Point p = circ.inter(ab)[0];
const long double ans = ((p - circ.c) ^ (b - circ.c)) / 2;
const long double th = (a - circ.c).ang(p - circ.c);
const long double d = circ.r * circ.r * th / 2;
if ((a - circ.c).toleft(b - circ.c) == 1)
return ans + d;
return ans - d;
}
const auto p = circ.inter(ab);
if (p.size() == 2 && Segment{a, b}.dis(circ.c) <= circ.r + eps) {
const long double ans = ((p[0] - circ.c) ^ (p[1] - circ.c)) / 2;
const long double th1 = (a - circ.c).ang(p[0] - circ.c), th2 = (b - circ.c).ang(p[1] - circ.c);
const long double d1 = circ.r * circ.r * th1 / 2, d2 = circ.r * circ.r * th2 / 2;
if ((a - circ.c).toleft(b - circ.c) == 1)
return ans + d1 + d2;
return ans - d1 - d2;
}
const long double th = (a - circ.c).ang(b - circ.c);
if ((a - circ.c).toleft(b - circ.c) == 1)
return circ.r * circ.r * th / 2;
return -circ.r * circ.r * th / 2;
};
long double ans = 0;
for (size_t i = 0; i < poly.p.size(); i++) {
const Point a = poly.p[i], b = poly.p[poly.nxt(i)];
ans += cal(circ, a, b);
}
return ans;
}
// 点集的凸包
// Andrew 算法,复杂度 O(nlogn)
Convex convexhull(vector<Point> p)
{
vector<Point> st;
if (p.empty())
return Convex{st};
sort(p.begin(), p.end());
const auto check = [](const vector<Point> &st, const Point &u) {
const auto back1 = st.back(), back2 = *prev(st.end(), 2);
return (back1 - back2).toleft(u - back1) <= 0;
};
for (const Point &u : p) {
while (st.size() > 1 && check(st, u))
st.pop_back();
st.push_back(u);
}
size_t k = st.size();
p.pop_back();
reverse(p.begin(), p.end());
for (const Point &u : p) {
while (st.size() > k && check(st, u))
st.pop_back();
st.push_back(u);
}
st.pop_back();
return Convex{st};
}
// 半平面交
// 排序增量法,复杂度 O(nlogn)
// 输入与返回值都是用直线表示的半平面集合
vector<Line> halfinter(vector<Line> l, const point_t lim = 1e9)
{
const auto check = [](const Line &a, const Line &b, const Line &c) { return a.toleft(b.inter(c)) < 0; };
// 无精度误差的方法,但注意取值范围会扩大到三次方
/*const auto check=[](const Line &a,const Line &b,const Line &c)
{
const Point p=a.v*(b.v^c.v),q=b.p*(b.v^c.v)+b.v*(c.v^(b.p-c.p))-a.p*(b.v^c.v);
return p.toleft(q)<0;
};*/
l.push_back({{-lim, 0}, {0, -1}});
l.push_back({{0, -lim}, {1, 0}});
l.push_back({{lim, 0}, {0, 1}});
l.push_back({{0, lim}, {-1, 0}});
sort(l.begin(), l.end());
deque<Line> q;
for (size_t i = 0; i < l.size(); i++) {
if (i > 0 && l[i - 1].v.toleft(l[i].v) == 0 && l[i - 1].v * l[i].v > eps)
continue;
while (q.size() > 1 && check(l[i], q.back(), q[q.size() - 2]))
q.pop_back();
while (q.size() > 1 && check(l[i], q[0], q[1]))
q.pop_front();
if (!q.empty() && q.back().v.toleft(l[i].v) <= 0)
return vector<Line>();
q.push_back(l[i]);
}
while (q.size() > 1 && check(q[0], q.back(), q[q.size() - 2]))
q.pop_back();
while (q.size() > 1 && check(q.back(), q[0], q[1]))
q.pop_front();
return vector<Line>(q.begin(), q.end());
}
// 点集形成的最小最大三角形
// 极角序扫描线,复杂度 O(n^2logn)
// 最大三角形问题可以使用凸包与旋转卡壳做到 O(n^2)
pair<point_t, point_t> minmax_triangle(const vector<Point> &vec)
{
if (vec.size() <= 2)
return {0, 0};
vector<pair<int, int>> evt;
evt.reserve(vec.size() * vec.size());
point_t maxans = 0, minans = numeric_limits<point_t>::max();
for (size_t i = 0; i < vec.size(); i++) {
for (size_t j = 0; j < vec.size(); j++) {
if (i == j)
continue;
if (vec[i] == vec[j])
minans = 0;
else
evt.push_back({i, j});
}
}
sort(evt.begin(), evt.end(), [&](const pair<int, int> &u, const pair<int, int> &v) {
const Point du = vec[u.second] - vec[u.first], dv = vec[v.second] - vec[v.first];
return argcmp()({du.y, -du.x}, {dv.y, -dv.x});
});
vector<size_t> vx(vec.size()), pos(vec.size());
for (size_t i = 0; i < vec.size(); i++)
vx[i] = i;
sort(vx.begin(), vx.end(), [&](int x, int y) { return vec[x] < vec[y]; });
for (size_t i = 0; i < vx.size(); i++)
pos[vx[i]] = i;
for (auto [u, v] : evt) {
const size_t i = pos[u], j = pos[v];
const size_t l = min(i, j), r = max(i, j);
const Point vecu = vec[u], vecv = vec[v];
if (l > 0)
minans = min(minans, abs((vec[vx[l - 1]] - vecu) ^ (vec[vx[l - 1]] - vecv)));
if (r < vx.size() - 1)
minans = min(minans, abs((vec[vx[r + 1]] - vecu) ^ (vec[vx[r + 1]] - vecv)));
maxans = max({maxans, abs((vec[vx[0]] - vecu) ^ (vec[vx[0]] - vecv)), abs((vec[vx.back()] - vecu) ^ (vec[vx.back()] - vecv))});
if (i < j)
swap(vx[i], vx[j]), pos[u] = j, pos[v] = i;
}
return {minans, maxans};
}
// 判断多条线段是否有交点
// 扫描线,复杂度 O(nlogn)
bool segs_inter(const vector<Segment> &segs)
{
if (segs.empty())
return false;
using seq_t = tuple<point_t, int, Segment>;
const auto seqcmp = [](const seq_t &u, const seq_t &v) {
const auto [u0, u1, u2] = u;
const auto [v0, v1, v2] = v;
if (abs(u0 - v0) <= eps)
return make_pair(u1, u2) < make_pair(v1, v2);
return u0 < v0 - eps;
};
vector<seq_t> seq;
for (auto seg : segs) {
if (seg.a.x > seg.b.x + eps)
swap(seg.a, seg.b);
seq.push_back({seg.a.x, 0, seg});
seq.push_back({seg.b.x, 1, seg});
}
sort(seq.begin(), seq.end(), seqcmp);
point_t x_now;
auto cmp = [&](const Segment &u, const Segment &v) {
if (abs(u.a.x - u.b.x) <= eps || abs(v.a.x - v.b.x) <= eps)
return u.a.y < v.a.y - eps;
return ((x_now - u.a.x) * (u.b.y - u.a.y) + u.a.y * (u.b.x - u.a.x)) * (v.b.x - v.a.x) < ((x_now - v.a.x) * (v.b.y - v.a.y) + v.a.y * (v.b.x - v.a.x)) * (u.b.x - u.a.x) - eps;
};
multiset<Segment, decltype(cmp)> s{cmp};
for (const auto [x, o, seg] : seq) {
x_now = x;
const auto it = s.lower_bound(seg);
if (o == 0) {
if (it != s.end() && seg.is_inter(*it))
return true;
if (it != s.begin() && seg.is_inter(*prev(it)))
return true;
s.insert(seg);
}
else {
if (next(it) != s.end() && it != s.begin() && (*prev(it)).is_inter(*next(it)))
return true;
s.erase(it);
}
}
return false;
}
// 多边形面积并
// 轮廓积分,复杂度 O(n^2logn),n为边数
// ans[i] 表示被至少覆盖了 i+1 次的区域的面积
vector<long double> area_union(const vector<Polygon> &polys)
{
const size_t siz = polys.size();
vector<vector<pair<Point, Point>>> segs(siz);
const auto check = [](const Point &u, const Segment &e) { return !((u < e.a && u < e.b) || (u > e.a && u > e.b)); };
auto cut_edge = [&](const Segment &e, const size_t i) {
const Line le{e.a, e.b - e.a};
vector<pair<Point, int>> evt;
evt.push_back({e.a, 0});
evt.push_back({e.b, 0});
for (size_t j = 0; j < polys.size(); j++) {
if (i == j)
continue;
const auto &pj = polys[j];
for (size_t k = 0; k < pj.p.size(); k++) {
const Segment s = {pj.p[k], pj.p[pj.nxt(k)]};
if (le.toleft(s.a) == 0 && le.toleft(s.b) == 0) {
evt.push_back({s.a, 0});
evt.push_back({s.b, 0});
}
else if (s.is_inter(le)) {
const Line ls{s.a, s.b - s.a};
const Point u = le.inter(ls);
if (le.toleft(s.a) < 0 && le.toleft(s.b) >= 0)
evt.push_back({u, -1});
else if (le.toleft(s.a) >= 0 && le.toleft(s.b) < 0)
evt.push_back({u, 1});
}
}
}
sort(evt.begin(), evt.end());
if (e.a > e.b)
reverse(evt.begin(), evt.end());
int sum = 0;
for (size_t i = 0; i < evt.size(); i++) {
sum += evt[i].second;
const Point u = evt[i].first, v = evt[i + 1].first;
if (!(u == v) && check(u, e) && check(v, e))
segs[sum].push_back({u, v});
if (v == e.b)
break;
}
};
for (size_t i = 0; i < polys.size(); i++) {
const auto &pi = polys[i];
for (size_t k = 0; k < pi.p.size(); k++) {
const Segment ei = {pi.p[k], pi.p[pi.nxt(k)]};
cut_edge(ei, i);
}
}
vector<long double> ans(siz);
for (size_t i = 0; i < siz; i++) {
long double sum = 0;
sort(segs[i].begin(), segs[i].end());
int cnt = 0;
for (size_t j = 0; j < segs[i].size(); j++) {
if (j > 0 && segs[i][j] == segs[i][j - 1])
segs[i + (++cnt)].push_back(segs[i][j]);
else
cnt = 0, sum += segs[i][j].first ^ segs[i][j].second;
}
ans[i] = sum / 2;
}
return ans;
}
// 圆面积并
// 轮廓积分,复杂度 O(n^2logn)
// ans[i] 表示被至少覆盖了 i+1 次的区域的面积
vector<long double> area_union(const vector<Circle> &circs)
{
const size_t siz = circs.size();
using arc_t = tuple<Point, long double, long double, long double>;
vector<vector<arc_t>> arcs(siz);
const auto eq = [](const arc_t &u, const arc_t &v) {
const auto [u1, u2, u3, u4] = u;
const auto [v1, v2, v3, v4] = v;
return u1 == v1 && abs(u2 - v2) <= eps && abs(u3 - v3) <= eps && abs(u4 - v4) <= eps;
};
auto cut_circ = [&](const Circle &ci, const size_t i) {
vector<pair<long double, int>> evt;
evt.push_back({-PI, 0});
evt.push_back({PI, 0});
int init = 0;
for (size_t j = 0; j < circs.size(); j++) {
if (i == j)
continue;
const Circle &cj = circs[j];
if (ci.r < cj.r - eps && ci.relation(cj) >= 3)
init++;
const auto inters = ci.inter(cj);
if (inters.size() == 1)
evt.push_back({atan2l((inters[0] - ci.c).y, (inters[0] - ci.c).x), 0});
if (inters.size() == 2) {
const Point dl = inters[0] - ci.c, dr = inters[1] - ci.c;
long double argl = atan2l(dl.y, dl.x), argr = atan2l(dr.y, dr.x);
if (abs(argl + PI) <= eps)
argl = PI;
if (abs(argr + PI) <= eps)
argr = PI;
if (argl > argr + eps) {
evt.push_back({argl, 1});
evt.push_back({PI, -1});
evt.push_back({-PI, 1});
evt.push_back({argr, -1});
}
else {
evt.push_back({argl, 1});
evt.push_back({argr, -1});
}
}
}
sort(evt.begin(), evt.end());
int sum = init;
for (size_t i = 0; i < evt.size(); i++) {
sum += evt[i].second;
if (abs(evt[i].first - evt[i + 1].first) > eps)
arcs[sum].push_back({ci.c, ci.r, evt[i].first, evt[i + 1].first});
if (abs(evt[i + 1].first - PI) <= eps)
break;
}
};
const auto oint = [](const arc_t &arc) {
const auto [cc, cr, l, r] = arc;
if (abs(r - l - PI - PI) <= eps)
return 2.0l * PI * cr * cr;
return cr * cr * (r - l) + cc.x * cr * (sin(r) - sin(l)) - cc.y * cr * (cos(r) - cos(l));
};
for (size_t i = 0; i < circs.size(); i++) {
const auto &ci = circs[i];
cut_circ(ci, i);
}
vector<long double> ans(siz);
for (size_t i = 0; i < siz; i++) {
long double sum = 0;
sort(arcs[i].begin(), arcs[i].end());
int cnt = 0;
for (size_t j = 0; j < arcs[i].size(); j++) {
if (j > 0 && eq(arcs[i][j], arcs[i][j - 1]))
arcs[i + (++cnt)].push_back(arcs[i][j]);
else
cnt = 0, sum += oint(arcs[i][j]);
}
ans[i] = sum / 2;
}
return ans;
}
void solve()
{
int n;
cin >> n;
cin >> xc >> yc >> r;
vector<Point> po(n);
for (int i = 0; i < n; i++)
cin >> po[i].x >> po[i].y;
Convex t1 = convexhull(po);
int ans = t1.get_area();
// for (auto i : t1.p) {
// cerr << i.x << " " << i.y << endl;
// }
// cerr << endl;
reverse(t1.p.begin(), t1.p.end());
ans = max(ans, (int)t1.get_area());
cout << ans << endl;
}
signed main()
{
ios::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int T = 1;
cin >> T;
while (T--)
solve();
return 0;
}
Details
Tip: Click on the bar to expand more detailed information
Test #1:
score: 100
Accepted
time: 1ms
memory: 3736kb
input:
3 5 1 1 1 0 0 1 0 5 0 3 3 0 5 6 2 4 1 2 0 4 0 6 3 4 6 2 6 0 3 4 3 3 1 3 0 6 3 3 6 0 3
output:
5 24 0
result:
ok 3 number(s): "5 24 0"
Test #2:
score: 0
Accepted
time: 0ms
memory: 4020kb
input:
1 6 0 0 499999993 197878055 -535013568 696616963 -535013568 696616963 40162440 696616963 499999993 -499999993 499999993 -499999993 -535013568
output:
0
result:
ok 1 number(s): "0"
Test #3:
score: -100
Wrong Answer
time: 39ms
memory: 3700kb
input:
6666 19 -142 -128 26 -172 -74 -188 -86 -199 -157 -200 -172 -199 -186 -195 -200 -175 -197 -161 -188 -144 -177 -127 -162 -107 -144 -90 -126 -87 -116 -86 -104 -89 -97 -108 -86 -125 -80 -142 -74 -162 -72 16 -161 -161 17 -165 -190 -157 -196 -154 -197 -144 -200 -132 -200 -128 -191 -120 -172 -123 -163 -138...
output:
5093 2862 2539 668 3535 7421 4883 8633 10181 1034 3332 3920 4372 2044 4996 4569 2251 4382 4175 1489 1154 3231 9728 1631 5086 19483 1692 6066 1945 1512 4488 5456 2675 11359 8557 14780 1496 9230 12878 8464 8182 4480 2303 2728 1739 2187 3385 4266 8344 909 4334 1518 948 10240 1449 2376 3180 4810 1443 30...
result:
wrong answer 2nd numbers differ - expected: '3086', found: '2862'