https://www.codewars.com/kata/5848565e273af816fb000449/rust

kata-5848565e273af816fb000449.rs

#![feature(assoc_char_funcs)]
use std::collections::VecDeque;
use std::iter::FromIterator;

fn main() -> Result<(), failure::Error> {
    let a = "Hello World";
    dbg!(a
        .split(" ")
        .fold(String::with_capacity(a.len()), |mut acc, w| {
            let mut s: VecDeque<char> = w.chars().collect();
            if s.len() > 2 {
                s.swap(1, s.len() - 1);
            }
            if let Some(c) = s.pop_front() {
                let v: Vec<char> = format!("{}", c as u32).chars().collect();
                v.into_iter().rev().for_each(|ch| s.push_front(ch));
            }
            acc.push_str(&String::from_iter(s));
            acc.push(' ');
            acc
        }).trim_end());

    Ok(())
}