This documentation is automatically generated by online-judge-tools/verification-helper
View the Project on GitHub Luzhiled/comp-geometry
// verification-helper: PROBLEM https://onlinejudge.u-aizu.ac.jp/courses/library/4/CGL/3/CGL_3_A #include "src/real-geometry/area/polygon-area.hpp" #include "src/real-geometry/class/polygon.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; } geometry::IoSetup(1); std::cout << geometry::polygon_area(poly) << std::endl; }
#line 1 "test/aoj/cgl/3_A.test.cpp" // verification-helper: PROBLEM https://onlinejudge.u-aizu.ac.jp/courses/library/4/CGL/3/CGL_3_A #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/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 6 "test/aoj/cgl/3_A.test.cpp" #line 8 "test/aoj/cgl/3_A.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; } geometry::IoSetup(1); std::cout << geometry::polygon_area(poly) << std::endl; }