leetcode JAVA Subsets II 4.26 难度系数4

Given a collection of integers that might contain duplicates, S, return all possible subsets.

Note:

• Elements in a subset must be in non-descending order.
• The solution set must not contain duplicate subsets.

  For example,
  If S = [1,2,2], a solution is:

  [
    [2],
    [1],
    [1,2,2],
    [2,2],
    [1,2],
    []
  ]

  public class Solution {
      public ArrayList
       
        > subsetsWithDup(int[] num) {
          ArrayList
        
         > results = new ArrayList
         
          >(); ArrayList
          
            result = new ArrayList
           
            (); Arrays.sort(num); dfs(num,0,result,results); return results; } private void dfs(int[] num, int step, ArrayList
            
              result, ArrayList
             
              > results) { if(!results.contains(result)) results.add(new ArrayList
              
               (result)); for(int i=step;i
               
                
  跟上题一样，可以2种方式加上去除重复。
               
              
             
            
           
          
         
        
       
  第二种去重：
  public class Solution {
      public ArrayList
        
         > subsetsWithDup(int[] num) {
          ArrayList
         
          > results = new ArrayList
          
           >(); ArrayList
           
             result = new ArrayList
            
             (); Arrays.sort(num); dfs(num,0,result,results); return results; } private void dfs(int[] num, int step, ArrayList
             
               result, ArrayList
              
               > results) { results.add(new ArrayList
               
                (result)); for(int i=step;i