Function ehr_gen 

pub fn ehr_gen(n: usize) -> GenBoxed<usize>

Generate all permutations by star transposition

The ehr_gen function generates all permutations of a given length using the star transposition algorithm.

Arguments:

• n: The parameter n represents the number of elements in the permutation. In the given example, n is set to 4, so it generates permutations of 4 elements.

Returns:

The function ehr_gen returns a GenBoxed<usize>, which is a boxed generator that yields usize values.

Examples

use ecgen::ehr_gen;
  
let mut perm = ["🍉", "🍌", "🍇", "🍏"];
let mut cnt = 1;
println!("{}", perm.concat());
for n in ehr_gen(perm.len()) {
    perm.swap(0, n);
    println!("{}", perm.concat());
    cnt += 1;
}

assert_eq!(cnt, 24);
assert_eq!(perm, ["🍏", "🍌", "🍇", "🍉"]);