题解 | #有重复项数字的全排列#和无重复思路一致，加上去重即可

public class Solution {
    public ArrayList<ArrayList<Integer>> permuteUnique(int[] num) {
        ArrayList<ArrayList<Integer>> res = new ArrayList<>();
        if(num == null || num.length == 0){
            return res;
        }
        Arrays.sort(num);
        doWork(res,num,0);
        return res;
    }
    
    private void doWork(ArrayList<ArrayList<Integer>> res,int[] num,int index){
        if(index == num.length - 1){
            ArrayList<Integer> list = new ArrayList<>();
            for(int i = 0;i<num.length;i++){
                list.add(num[i]);
            }
             //第二道防线 也是终极防线
            if(!res.contains(list)){
                res.add(list);
            }
        } else {
             for(int i = index;i<num.length;i++){
                 //第一道防线
                 if(i != index && num[index] == num[i]){
                     continue;
                 }
                 swap(num,index,i);
                 int[] afterOrder = new int[num.length];
                 for(int j = 0;j<num.length;j++){
                     afterOrder[j] = num[j];
                 }
                 quickOrder(afterOrder,index + 1,afterOrder.length - 1);
                 doWork(res,afterOrder,index + 1);
                 swap(num,i,index);
            }
        }
    }
    
    private void swap(int[] num,int index,int i){
        int temp = num[i];
        num[i] = num[index];
        num[index] = temp;
    }
    
    private void quickOrder(int[] num,int begin,int end){
        if(begin >= end){
            return;
        }
        int left = begin;
        int right = end;
        int res = num[left];
        while(left < right){
            while(left < right && num[right] > res){
                right --;
            }
            if(left < right){
                num[left] = num[right];
                left ++;
            }
            while(left < right && num[left] < res){
                left ++;
            }
            if(left < right){
                num[right] = num[left];
                right --;
            }
        }
        num[left] = res;
        quickOrder(num,begin,left - 1);
        quickOrder(num,left + 1,end);
    }
}