Permutations II

Given a collection of numbers, nums, that might contain duplicates, return all possible unique permutations in any order.

public IList<IList<int>> PermuteUnique(int[] nums)
{
    IList<IList<int>> result = new List<IList<int>>();
    Array.Sort(nums);
    bool[] used = new bool[nums.Length];
    List<int> temp = new List<int>();
    PermuteUnique(nums, temp, result, used);
    return result;
}

public void PermuteUnique(int[] nums, List<int> temp, IList<IList<int>> result, bool[] used)
{
    if (temp.Count == nums.Length)
    {
        result.Add(temp.ToList());
        return;
    }
    for (int i = 0; i < nums.Length; i++)
    {
        if (used[i] || (i > 0 && nums[i] == nums[i - 1] && !used[i - 1])) continue;
        temp.Add(nums[i]);
        used[i] = true;
        PermuteUnique(nums, temp, result, used);
        temp.RemoveAt(temp.Count - 1);
        used[i] = false;
    }
}