Rust: Sort a vector of ints and preserve indices

vecsort_with_index.rs

        
use std::cmp::Ordering;

fn main() {
  fn sort_pairs<'r,'s>((_,a): &'r (usize, &i32), (_,b): &'s (usize, &i32)) -> Ordering {
    if a > b { Ordering::Greater }
    else if b > a { Ordering::Less }
    else { Ordering::Equal}
  }
        
  let mut v: Vec<(usize,&i32)> = [1, 3, 2].iter().enumerate().collect();
  v.sort_by(sort_pairs);
  println!("{:?}", v);
}