combination sum

class  {
    public List<List<Integer>> combinationSum(int[] candidates, int target) {
        List<List<Integer>> list=new ArrayList<>();
        Arrays.sort(candidates);
        backTrack(list,new ArrayList<>(),candidates,target,0);
        return list;
    }
    public void backTrack(List<List<Integer>> list,ArrayList<Integer> tempList,int [] nums,int remain,int start)
    {
        if(remain<0)
            return;
      else  if(remain==0)
        {
            list.add(new ArrayList<>(tempList));
        }
        else
        {
        for(int i=start;i<nums.length;i++)
        {
            tempList.add(nums[i]);
            backTrack(list,tempList,nums,remain-nums[i],i);
            tempList.remove(tempList.size()-1);
        }
        }
    }
}