Function generate

Helper function for the `permute` function to generate distinct permutations recursively. # Arguments `nums` - A reference to the sorted slice of integers. `current` - A mutable reference to the vector holding the current permutation. `used` - A mutable reference to a vector tracking which elements are used. `permutations` - A mutable reference to the vector holding all generated distinct permut

(
    nums: &[isize],
    current: &mut Vec<isize>,
    used: &mut Vec<bool>,
    permutations: &mut Vec<Vec<isize>>,
)