478. Generate Random Point in a Circle

Given the radius and x-y positions of the center of a circle, write a function randPoint which generates a uniform random point in the circle.

Note:

• input and output values are in floating-point.
• radius and x-y position of the center of the circle is passed into the class constructor.
• a point on the circumference of the circle is considered to be in the circle.
• randPoint returns a size 2 array containing x-position and y-position of the random point, in that order.

class Solution {
private:
    double r;
    double x;
    double y;
public:
    Solution(double radius, double x_center, double y_center) : r(radius), x(x_center), y(y_center) {}

    vector<double> randPoint() {
        double theta = rand() * 1.0 / RAND_MAX * 2 * M_PI;
        double hypotenuse = sqrt(rand() * 1.0 / RAND_MAX) * r;
        return vector<double> {cos(theta) * hypotenuse + x, sin(theta) * hypotenuse + y};
    }
};

/**
 * Your Solution object will be instantiated and called as such:
 * Solution* obj = new Solution(radius, x_center, y_center);
 * vector<double> param_1 = obj->randPoint();
 */

Reference

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