47 Permutations II

public class Solution {    List<List<Integer>> res = new ArrayList<List<Integer>>();public List<List<Integer>> permuteUnique(int[] nums) {        if(nums==null||nums.length==0){        return res;        }        Arrays.sort(nums);        ArrayList<Integer> tmp = new ArrayList<Integer>();        dfs(tmp,0,nums);        return res;    }void dfs(List<Integer> tmp, int depth, int[] nums){int len = nums.length;if(depth==len){res.add(tmp);return;}for(int i=0;i<len;++i){if(i==0||nums[i]!=nums[i-1]){int c1 = 0,c2 = 0;int tsize = tmp.size();for(int j=0;j<tsize;++j){if(tmp.get(j)==nums[i]) ++c1;}for(int k=0;k<len;++k){if(nums[k]==nums[i]) ++c2;}if(c1 < c2){List<Integer> tt = new ArrayList<Integer>(tmp);tt.add(nums[i]);dfs(tt, depth + 1, nums);}}}}}