quest – Rust: Control flow

Core Beginner

02 Control flow

Loops and conditionals: sum a range, then write the classic fizzbuzz for a single number.

Step 3 / 3

Count Collatz steps in collatz_steps: even goes to n / 2, odd goes to 3n + 1; stop at 1.

Hints

while n != 1 { ... } with a step counter.
if/else is an expression: n = if n % 2 == 0 { n / 2 } else { 3 * n + 1 };.

02_control_flow.rs

// how many steps to reach 1?  even -> n/2, odd -> 3n+1
fn collatz_steps(mut n: u64) -> u32 {
    todo!()
}

Reset to starterCompiled in a sandbox; hidden checks must pass.

Reveal solution

fn collatz_steps(mut n: u64) -> u32 {
    let mut steps = 0;
    while n != 1 {
        n = if n % 2 == 0 { n / 2 } else { 3 * n + 1 };
        steps += 1;
    }
    steps
}