64 lines
2.3 KiB
C++
64 lines
2.3 KiB
C++
#include <iostream>
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#include <cmath>
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#include <tuple>
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struct point { double x, y; };
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bool operator==(const point& lhs, const point& rhs)
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{ return std::tie(lhs.x, lhs.y) == std::tie(rhs.x, rhs.y); }
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enum result_category { NONE, ONE_COINCEDENT, ONE_DIAMETER, TWO, INFINITE };
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using result_t = std::tuple<result_category, point, point>;
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double distance(point l, point r)
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{ return std::hypot(l.x - r.x, l.y - r.y); }
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result_t find_circles(point p1, point p2, double r)
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{
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point ans1 { 1/0., 1/0.}, ans2 { 1/0., 1/0.};
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if (p1 == p2) {
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if(r == 0.) return std::make_tuple(ONE_COINCEDENT, p1, p2 );
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else return std::make_tuple(INFINITE, ans1, ans2);
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}
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point center { p1.x/2 + p2.x/2, p1.y/2 + p2.y/2};
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double half_distance = distance(center, p1);
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if(half_distance > r) return std::make_tuple(NONE, ans1, ans2);
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if(half_distance - r == 0) return std::make_tuple(ONE_DIAMETER, center, ans2);
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double root = sqrt(pow(r, 2.l) - pow(half_distance, 2.l)) / distance(p1, p2);
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ans1.x = center.x + root * (p1.y - p2.y);
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ans1.y = center.y + root * (p2.x - p1.x);
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ans2.x = center.x - root * (p1.y - p2.y);
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ans2.y = center.y - root * (p2.x - p1.x);
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return std::make_tuple(TWO, ans1, ans2);
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}
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void print(result_t result, std::ostream& out = std::cout)
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{
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point r1, r2; result_category res;
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std::tie(res, r1, r2) = result;
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switch(res) {
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case NONE:
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out << "There are no solutions, points are too far away\n"; break;
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case ONE_COINCEDENT: case ONE_DIAMETER:
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out << "Only one solution: " << r1.x << ' ' << r1.y << '\n'; break;
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case INFINITE:
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out << "Infinitely many circles can be drawn\n"; break;
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case TWO:
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out << "Two solutions: " << r1.x << ' ' << r1.y << " and " << r2.x << ' ' << r2.y << '\n'; break;
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}
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}
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int main()
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{
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constexpr int size = 5;
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const point points[size*2] = {
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{0.1234, 0.9876}, {0.8765, 0.2345}, {0.0000, 2.0000}, {0.0000, 0.0000},
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{0.1234, 0.9876}, {0.1234, 0.9876}, {0.1234, 0.9876}, {0.8765, 0.2345},
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{0.1234, 0.9876}, {0.1234, 0.9876}
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};
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const double radius[size] = {2., 1., 2., .5, 0.};
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for(int i = 0; i < size; ++i)
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print(find_circles(points[i*2], points[i*2 + 1], radius[i]));
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}
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