Combination Sum II

Description
Given an array num and a number target. Find all unique combinations in num where the numbers sum to target.

public class Solution {
    /**
     * @param num: Given the candidate numbers
     * @param target: Given the target number
     * @return: All the combinations that sum to target
     */
    public List<List<Integer>> combinationSum2(int[] num, int target) {
        // write your code here
        List<List<Integer>> results = new ArrayList<>() ;
        if(num == null  || num.length == 0){
          return results ;
        }
        Arrays.sort(num) ;
        helper(num , target, 0 , results, new ArrayList<Integer>()) ;
        return results ;
    }
    public void helper(int[] num, int remintarget , int start , List<List<Integer>> results, List<Integer> subset){
        if(remintarget == 0){
          results.add(new ArrayList<Integer>(subset)) ;
        }
        for(int i = start ; i < num.length ; i++ ){
          if(remintarget < num[i]){
            break ;
          }
          if(i != start && num[i] == num[i-1]){
               continue ;
          }
          subset.add(num[i]);
          helper(num , remintarget - num[i] , i+1 , results , subset) ;
          subset.remove(subset.size()-1);
        }
    }
}