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View the Project on GitHub Luzhiled/comp-geometry
// verification-helper: PROBLEM https://onlinejudge.u-aizu.ac.jp/courses/library/4/CGL/4/CGL_4_C // verification-helper: ERROR 0.00001 #include "src/real-geometry/area/polygon-area.hpp" #include "src/real-geometry/class/line.hpp" #include "src/real-geometry/class/polygon.hpp" #include "src/real-geometry/convex/convex-cut.hpp" #include "src/real-geometry/utility/io-set.hpp" #include <iostream> int main() { using R = long double; int n; std::cin >> n; geometry::polygon<R> poly(n); for (auto &p: poly) { std::cin >> p; } int q; std::cin >> q; while (q--) { geometry::line<R> l; std::cin >> l.a >> l.b; auto c = geometry::convex_cut(poly, l); std::cout << geometry::polygon_area(c) << std::endl; } }
#line 1 "test/aoj/cgl/4_C.test.cpp" // verification-helper: PROBLEM https://onlinejudge.u-aizu.ac.jp/courses/library/4/CGL/4/CGL_4_C // verification-helper: ERROR 0.00001 #line 2 "src/real-geometry/area/polygon-area.hpp" #line 2 "src/real-geometry/common/size-alias.hpp" #include <cstddef> namespace geometry { using isize = std::ptrdiff_t; using usize = std::size_t; } #line 2 "src/real-geometry/class/polygon.hpp" #line 2 "src/real-geometry/class/point.hpp" #line 2 "src/real-geometry/class/vector.hpp" #include <complex> #include <iostream> namespace geometry { template< typename R > class vec2d : public std::complex< R > { using complex = std::complex< R >; public: using complex::complex; vec2d(const complex &c): complex::complex(c) {} const R x() const { return this->real(); } const R y() const { return this->imag(); } friend vec2d operator*(const vec2d &v, const R &k) { return vec2d(v.x() * k, v.y() * k); } friend vec2d operator*(const R &k, const vec2d &v) { return vec2d(v.x() * k, v.y() * k); } friend std::istream &operator>>(std::istream &is, vec2d &v) { R x, y; is >> x >> y; v = vec2d(x, y); return is; } }; } #line 4 "src/real-geometry/class/point.hpp" #include <vector> namespace geometry { template< typename R > using point = vec2d<R>; template< typename R > using points = std::vector< point< R > >; } #line 4 "src/real-geometry/class/polygon.hpp" #line 6 "src/real-geometry/class/polygon.hpp" namespace geometry { template< typename R > using polygon = std::vector< point<R> >; template< typename R > using polygons = std::vector< polygon<R> >; } #line 2 "src/real-geometry/operation/cross-product.hpp" #line 4 "src/real-geometry/operation/cross-product.hpp" namespace geometry { template< typename R > R cross_product(const vec2d<R> &a, const vec2d<R> &b) { return a.x() * b.y() - a.y() * b.x(); } } #line 2 "src/real-geometry/utility/next-idx.hpp" #line 4 "src/real-geometry/utility/next-idx.hpp" namespace geometry { inline usize next_idx(usize idx, usize size) { return idx + 1 == size ? 0 : idx + 1; } } #line 7 "src/real-geometry/area/polygon-area.hpp" namespace geometry { template< typename R > R polygon_area(const polygon<R> &poly) { usize n = poly.size(); R res = 0; for (usize i = 0; i < n; ++i) { res += cross_product(poly[i], poly[next_idx(i, n)]); } return res / 2; } } #line 2 "src/real-geometry/class/line.hpp" #line 2 "src/real-geometry/utility/equals/vector.hpp" #line 2 "src/real-geometry/utility/equals/real-number.hpp" #line 2 "src/real-geometry/utility/sign.hpp" #line 2 "src/real-geometry/common/const/eps.hpp" #line 2 "src/real-geometry/common/float-alias.hpp" namespace geometry { using f80 = long double; using f64 = double; } #line 4 "src/real-geometry/common/const/eps.hpp" namespace geometry { inline static f80 &eps() { static f80 EPS = 1e-10; return EPS; } void set_eps(f80 EPS) { eps() = EPS; } } #line 2 "src/real-geometry/numbers/sign.hpp" #line 2 "src/real-geometry/common/int-alias.hpp" namespace geometry { using i32 = int; using i64 = long long; } #line 4 "src/real-geometry/numbers/sign.hpp" namespace geometry::number::sign { constexpr i32 PLUS = +1; constexpr i32 ZERO = 0; constexpr i32 MINUS = -1; } #line 5 "src/real-geometry/utility/sign.hpp" namespace geometry { using namespace geometry::number::sign; template< typename R > inline int sign(R r) { if (r < -eps()) return MINUS; if (r > +eps()) return PLUS; return ZERO; } } #line 4 "src/real-geometry/utility/equals/real-number.hpp" namespace geometry { template< typename R > bool equals(R a, R b) { return sign(a - b) == 0; } } #line 5 "src/real-geometry/utility/equals/vector.hpp" namespace geometry { template< typename R > bool equals(const vec2d<R> &a, const vec2d<R> &b) { return equals(a.x(), b.x()) and equals(a.y(), b.y()); } } #line 5 "src/real-geometry/class/line.hpp" #include <cassert> #line 8 "src/real-geometry/class/line.hpp" namespace geometry { template< typename R > class line { using P = point<R>; public: P a, b; line() = default; line(P a, P b) : a(a), b(b) { assert(not equals(a, b)); } }; template< typename R > using lines = std::vector< line<R> >; } #line 2 "src/real-geometry/convex/convex-cut.hpp" #line 9 "src/real-geometry/convex/convex-cut.hpp" namespace geometry { template< typename R > polygon<R> convex_cut(const polygon<R> &poly, const line<R> &l) { usize n = poly.size(); polygon<R> res; for (usize i = 0; i < n; i++) { usize j = next_idx(i, n); R cf = cross_product<R>(l.a - poly[i], l.b - poly[i]); R cs = cross_product<R>(l.a - poly[j], l.b - poly[j]); if (sign(cf) >= 0) res.emplace_back(poly[i]); if (sign(cf) * sign(cs) < 0) { R s = cross_product<R>(poly[j] - poly[i], l.a - l.b); R t = cross_product<R>(l.a - poly[i], l.a - l.b); res.emplace_back(poly[i] + t / s * (poly[j] - poly[i])); } } return res; } } #line 2 "src/real-geometry/utility/io-set.hpp" #include <iomanip> namespace geometry { class IoSetup { using u32 = unsigned int; void set(std::ostream &os, u32 precision) { os << std::fixed << std::setprecision(precision); } public: IoSetup(u32 precision = 15) { std::cin.tie(0); std::ios::sync_with_stdio(0); set(std::cout, precision); set(std::cerr, precision); } } iosetup; } #line 9 "test/aoj/cgl/4_C.test.cpp" #line 11 "test/aoj/cgl/4_C.test.cpp" int main() { using R = long double; int n; std::cin >> n; geometry::polygon<R> poly(n); for (auto &p: poly) { std::cin >> p; } int q; std::cin >> q; while (q--) { geometry::line<R> l; std::cin >> l.a >> l.b; auto c = geometry::convex_cut(poly, l); std::cout << geometry::polygon_area(c) << std::endl; } }