Combination Sum II

问题：给定一个无重复的数组candidates和一个目标值target，根据数组中的元素输出和为目标值的所有可能组合，数组中的每个元素不能多次使用，输出结果不能有重复的组合。数组中的数和target均为正数

示例：

输入：candidates = [1,2,3,5,6] target = 6

输出：[[1,2,3],[6]]

解决思路：对candidates进行排序，之后遍历，并相应的减小target，递归进行，直到target为0.

Python代码：

class Solution(object):
    def combinationSum2(self, candidates, target):
        """
        :type candidates: List[int]
        :type target: int
        :rtype: List[List[int]]
        """
        self.out = []
        candidates.sort()
        self.Sum(candidates,target)
        return self.out
        
    def Sum(self,candidates,target,res=[],use=[]):
        if not target:
            self.out.append(res)
            return
        for i in range(len(candidates)):
　　　　　　　 # Avoid duplicate usage of the same elements in cnadidates
            if i > 0 and candidates[i] == candidates[i-1]:
                continue
            can = candidates[i]
            if can <= target:
                # To avoid duplicate usage of elements and duplicate combinations, input "candidaters[i+1:] instead of candidates"
                self.Sum(candidates[i+1:],target-can,res+[can])
            else:
                break