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:

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

Example 1:

```Input:
["Solution","randPoint","randPoint","randPoint"]
[[1,0,0],[],[],[]]
Output: [null,[-0.72939,-0.65505],[-0.78502,-0.28626],[-0.83119,-0.19803]]
```

Example 2:

```Input:
["Solution","randPoint","randPoint","randPoint"]
[[10,5,-7.5],[],[],[]]
Output: [null,[11.52438,-8.33273],[2.46992,-16.21705],[11.13430,-12.42337]]```

Explanation of Input Syntax:

The input is two lists: the subroutines called and their arguments. `Solution`'s constructor has three arguments, the radius, x-position of the center, and y-position of the center of the circle. `randPoint` has no arguments. Arguments are always wrapped with a list, even if there aren't any.

478. Generate Random Point in a Circle
``````use rand::prelude::*;

struct Solution {
x_center: f64,
y_center: f64,
}

impl Solution {
fn new(radius: f64, x_center: f64, y_center: f64) -> Self {
Solution {
x_center,
y_center,
rng,
}
}

fn rand_point(&mut self) -> Vec<f64> {
while x * x + y * y > self.radius * self.radius {
}
vec![x + self.x_center, y + self.y_center]
}
}
``````