class Solution {
    public List<List<Integer>> permute(int[] nums) {
        Queue<List<Integer>> queue = new LinkedList<>();

        queue.offer(new ArrayList<>());
        int n = nums.length;

        while(n-- != 0) {
            int size = queue.size();
            for(int i = 0; i < size; i++) {
                List<Integer> entry = queue.poll();
                for(int j = 0; j < nums.length; j++) {
                    if(entry.contains(nums[j])) continue;
                    List<Integer> copy = new ArrayList<>(entry);
                    copy.add(nums[j]);
                    queue.offer(copy);
                }
            }

        }
        return new ArrayList<>(queue);
    }
}