introduction.md

Introduction

There are many ways to solve Secret Handshake. One approach is to iterate only once, even when the signs are to be reversed.

General guidance

Something to consider is to keep the number of iterations at a minimum to get the best performance. However, if that is felt to adversely impact readability, then to use a series of if statements and then reverse is also valid.

Approach: Iterate once

const SIGNS: [&'static str; 4] = ["wink", "double blink", "close your eyes", "jump"];
const REVERSE_SIGNS: u8 = 16;

pub fn actions(n: u8) -> Vec<&'static str> {
    let (mut action, action_incr, end) = match n & REVERSE_SIGNS {
        0 => (0, 1, 4),
        _ => (3, -1, -1),
    };
    let mut output: Vec<&'static str> = Vec::new();
    
    loop {
        if action == end {
            break;
        }
        if (n & (1 << action)) != 0 {
            output.push(SIGNS[action as usize])
        }
        action += action_incr
    }
    output
}

For more information, check the Iterate once approach.