Height equalizer

equalizer.rs

/// Tower equaliser: givern list of tower heights return the minimum number
/// of moves required to obtain tower of the same height or return "No solution"
fn towers(t: &[u32]) -> Option<u32> {
    let mut moves: u32 = 0;
    let mut n = t.to_vec();
    let max_moves: u32 = n.iter().sum();
    loop {
        let imax = match n.iter().enumerate().max_by(|&(_, x), &(_, y)| x.cmp(&y)) {
            Some((m, _)) => m,
            _ => usize::MIN,
        };
        let imin = match n.iter().enumerate().min_by(|&(_, x), &(_, y)| x.cmp(&y)) {
            Some((m, _)) => m,
            _ => usize::MAX,
        };
        if n[imax] == n[imin] {
            return Some(moves);
        }
        n[imax] -= 1;
        n[imin] += 1;
        moves += 1;
        if moves >= max_moves {
            return None;
        }
    }
}

fn main() {
    let mut args = std::env::args();
    let exe = match args.next() {
        Some(p) => p,
        _ => "".to_string(),
    };
    let n: Vec<u32> = args.flat_map(|x| x.parse()).collect();
    if n.is_empty() {
        eprintln!("Error, usage: {} SPACE SEPARATED NUMBERS", exe);
        std::process::exit(1);
    }
    if let Some(r) = towers(&n) {
        println!("Number of moves: {}", r);
    } else {
        println!("No solution");
    }
}