LeetCde----40. Combination Sum II

Given a collection of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums to T.

Each number in C may only be used once in the combination.

Note:

• All numbers (including target) will be positive integers.
• The solution set must not contain duplicate combinations.

For example, given candidate set [10, 1, 2, 7, 6, 1, 5] and target 8, 
A solution set is: 

[
  [1, 7],
  [1, 2, 5],
  [2, 6],
  [1, 1, 6]
]

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注意：有重复元素，会导致出现相同集合

public class Solution {
    
    List> result=new ArrayList>();
    
    public List> combinationSum2(int[] candidates, int target) {
        if(candidates.length<=0){return result;}
        Arrays.sort(candidates);
        helper(new ArrayList(),candidates,0,target);
        return result;
    }
    public void helper(ArrayList path,int [] candidates,int from,int target){
        if(target==0){
            List list =new ArrayList<>(path);
            result.add(list);
        }else{
            int weiyi=Integer.MAX_VALUE;;//防止重复
            for(int i=from;i