Some useful scripts to explore the 3x+1 problem explained in: https://www.youtube.com/watch?v=094y1Z2wpJg

README.md

Note: You will need to have Python 3 and Rust installed on your computer!

To check how many iterations a number takes to reach 1, run the number_of_iterations.py file as follows:

python3 number_of_iterations.py

Output:

Enter an integer: 9
9 took 19 iterations!

To check not only the number of iterations it takes for each number in a range to reach 1 but also which number takes the most iterations, run the max_iterations.rs file as follows:

Be sure to change the values of MIN and MAX which are used for the range.

rustc -O max_iterations.rs && ./max_iterations

Output:

1 took 0 iterations!
2 took 1 iterations!
3 took 7 iterations!
4 took 2 iterations!
5 took 5 iterations!
6 took 8 iterations!
7 took 16 iterations!
8 took 3 iterations!
9 took 19 iterations!
10 took 6 iterations!
Max iterations (19) by number 9!

max_iterations.rs

const MIN: usize = 1;
const MAX: usize = 10;

fn is_odd(n: usize) -> bool {
    n % 2 == 1
}

fn main() {
    let mut max_iterations = 0;
    let mut max_iterations_by_number = 0;

    for i in MIN..=MAX {
        let mut number = i;
        print!("{} took ", number);

        let mut counter = 0;

        while number != 1 {
            if is_odd(number) {
                number = (number * 3) + 1;
            } else {
                number /= 2;
            }
            counter += 1;
        }

        if counter > max_iterations {
            max_iterations = counter;
            max_iterations_by_number = i;
        }

        println!("{} iterations!", counter)
    }

    println!(
        "Max iterations ({}) by number {}!",
        max_iterations, max_iterations_by_number
    )
}

number_of_iterations.py

def get_integer() -> int:
    msg = "Enter an integer: "
    while True:
        try:
            return int(input(msg))
        except Exception as _:
            msg = "Please enter a valid integer: "


def is_odd(n: int) -> bool:
    return n % 2 == 1


number = get_integer()
print(f"{number} took ", end="")

counter = 0
while number != 1:
    if is_odd(number):
        number = (number * 3) + 1
    else:
        number //= 2
    counter += 1

print(f"{counter} iterations!")