Method permute_unique

47. Permutations II/src/main.rs:8–19

(mut nums: Vec<i32>)

impl Solution {
    pub fn permute_unique(mut nums: Vec<i32>) -> Vec<Vec<i32>> {
        nums.sort();
        let mut n = nums.clone();
        let mut res = vec![];
        res.push(n.clone());
        Self::next_permutation(&mut n);
        while n != nums {
            res.push(n.clone());
            Self::next_permutation(&mut n);
        }
        res
    }

    pub fn next_permutation(nums: &mut Vec<i32>) {
        if nums.len() <= 1 { return }