#![allow(dead_code, deprecated, unused_variables, unused_mut)]
fn main() {
    let mut s = [10, 40, 30, 20, 60, 50];
    for group in s.rsplitn_mut(2, |num| *num % 3 == 0) {
        group[0] = 1;
    }
    assert_eq!(s, [1, 40, 30, 20, 60, 1]);
}