Combination sum-Sort list of list nested list https://www.interviewbit.com/problems/combination-sum/

CombinationSum.java

//https://www.interviewbit.com/problems/combination-sum/
public class Solution {
    public ArrayList<ArrayList<Integer>> combinationSum(ArrayList<Integer> A, int B) {
ArrayList<ArrayList<Integer>> big=new ArrayList<ArrayList<Integer>>();
    if(A.size()==0){
        return big;
    }
    Collections.sort(A);
        combination(big,0,A,B,new ArrayList<Integer>(),B);
        Collections.sort(big,new Comparator<ArrayList<Integer>>(){
                
                       @Override
             public int compare(ArrayList<Integer> o1, ArrayList<Integer> o2) {
                for (int i = 0; i < Math.min(o1.size(), o2.size()); i++) {
                    int c = o1.get(i).compareTo(o2.get(i));
                        if (c != 0) {
                                return c;
                            }
                    }
                    return Integer.compare(o1.size(), o2.size());
            }           
        });
        
 
        return big;
    }


    
    public void combination(ArrayList<ArrayList<Integer>> big,int start,ArrayList<Integer> A,int B,ArrayList<Integer> small,int sum){
        if(sum<0){
            return;
        }
        else if(sum==0){
            ArrayList<Integer> cloneLs=new ArrayList<Integer>(small);
            Collections.sort(cloneLs);
            if(!big.contains(cloneLs)){
            big.add(cloneLs);
            }
        }
        else{
        for(int i=start;i<A.size();i++){
          
               
                small.add(A.get(i));
                combination(big,start+1,A,B,small,sum-A.get(i));
                combination(big,start,A,B,small,sum-A.get(i));
            
            //}
            if(small.size()>0){
                //sum-=small.get(small.size()-1);
                small.remove(small.size()-1);
            }
        }
        }
        
    }
   
}