Random in Rust 1.55

In Rust 1.55, you can use the standard library's rand crate to generate random numbers. Here's how:

1. Add rand to your dependencies in Cargo.toml:

   [dependencies]
   rand = "0.8.4"
   

2. Import the Rng trait and the thread_rng function from the rand crate:

   use rand::Rng;
   use rand::thread_rng;
   

3. Use thread_rng to create a random number generator:

   let mut rng = thread_rng();
   

4. Use methods on the Rng trait to generate random numbers. Examples:

- Generate a random integer between 1 and 100 (inclusive):

     let n = rng.gen_range(1..=100);
     

- Generate a random boolean:

     let b = rng.gen_bool(0.5); // 50% chance of true/false
     

     let f = rng.gen::();
     

- Generate a random integer from a normal distribution with mean 0 and standard deviation 1:

     let n = rng.gen::().powf(2.0).ln() * (-2.0).sqrt() as i32;