Combination Sum I and II

More typical helper topics, and now I'm not quite clear about DFS and so on, can only use helper to collectively, you know that tune on the line

 Public classSolution { PublicArraylist<arraylist<integer>> Combinationsum (int[] candidates,inttarget) {ArrayList<ArrayList<Integer>> res =NewArraylist<arraylist<integer>>();        Arrays.sort (candidates); if(Candidates = =NULL|| CANDIDATES.LENGTH&LT;1)returnRes; Helper (candidates, target, RES,NewArraylist<integer> (), 0); returnRes; }     Public voidHelperint[] C,intt,arraylist<arraylist<integer>> Res, arraylist<integer> item,intstart) {        if(0==t) {Res.add (NewArraylist<integer> (item));//Res.add (item);            return;//Speed        }        if(0>t)return;  for(intI=start; i< c.length; i++){            if(I>start && C[i-1]==c[i])Continue;            Item.add (C[i]); Helper (c, T-c[i], res, item, i);//If I becomes i+1, then the repetition element is not allowed to appear, and I, and the loop starts from I=start, allows the possibility of repeating elements to build the target, and resolves the IIItem.remove (Item.size ()-1); }    }}

Combination Sum I and II