class Solution {
private List[HTML_REMOVED]> paths = new ArrayList<>();

public List<List<Integer>> permutation(int[] nums) {

    boolean[] st = new boolean[nums.length];
    Integer[] path = new Integer[nums.length];
    DFS(0, nums, st, path);
    return paths;

}

public void DFS(int n, int[] nums, boolean[] st, Integer[] path){
    if(n = = nums.length){
        Integer[] p = new Integer[path.length];
        System.arraycopy(path, 0, p, 0, path.length);
        paths.add(Arrays.asList(p));
        return;
    }
    for(int i=0; i<nums.length;i++){

        if(!st[i]){
            int j;
            for(j=i-1;j>=0; j--){
                if(nums[j]==nums[i])break;
            }
            if(i>=1&&j>=0&&nums[j]==nums[i]&&!st[j])continue;//相同元素规定顺序 相同的元素不能出现在后边
            path[n] = nums[i];
            st[i] = true;
            DFS(n+1, nums, st, path);
            st[i] = false;
        }
    }
    return;
}

}