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.
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.
Rust Solution
use rand::prelude::*;
struct Solution {
radius: f64,
x_center: f64,
y_center: f64,
rng: ThreadRng,
}
impl Solution {
fn new(radius: f64, x_center: f64, y_center: f64) -> Self {
let rng = rand::thread_rng();
Solution {
radius,
x_center,
y_center,
rng,
}
}
fn rand_point(&mut self) -> Vec<f64> {
let mut x = self.rng.gen_range(-self.radius, self.radius);
let mut y = self.rng.gen_range(-self.radius, self.radius);
while x * x + y * y > self.radius * self.radius {
x = self.rng.gen_range(-self.radius, self.radius);
y = self.rng.gen_range(-self.radius, self.radius);
}
vec![x + self.x_center, y + self.y_center]
}
}
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