Function parity_vector 

pub fn parity_vector(n: u64) -> Option<Vec<CollatzParity>>

Returns the parity pattern for the trajectory from n to 1.

The returned vector includes the starting value and every nonterminal value in the trajectory, but it excludes the final 1. For n == 1, this means the parity vector is empty.

Returns None when n == 0 or when a checked odd step overflows.

Examples

use use_collatz::{CollatzParity, parity_vector};

assert_eq!(
    parity_vector(6),
    Some(vec![
        CollatzParity::Even,
        CollatzParity::Odd,
        CollatzParity::Even,
        CollatzParity::Odd,
        CollatzParity::Even,
        CollatzParity::Even,
        CollatzParity::Even,
        CollatzParity::Even,
    ])
);
assert_eq!(parity_vector(1), Some(vec![]));