递归和回溯_leetcode40-经典的组合去重问题

class Solution(object):
    def combinationSum2(self, candidates, target):
        """
        :type candidates: List[int]
        :type target: int
        :rtype: List[List[int]]
        """
        self.res = []
        self.old = None

        candidates = sorted(candidates)


        self.generateCombinatio(candidates,target,0,[])

        print self.res

        return self.res



    def generateCombinatio(self,candidates,target,start ,ans):

        if sum(ans) == target:
            self.res.append(ans[0:])
            return

        if sum(ans) > target:
            return



        if self.old == None:

            for i in range(start,len(candidates)):
                if candidates[i] != self.old:
                    ans.append(candidates[i])
                    self.generateCombinatio(candidates,target,i+1,ans)
                    self.old = ans.pop()
                else:
                    continue

        else:
            for i in range(start, len(candidates)):

                if candidates[i] != self.old:
                    ans.append(candidates[i])
                    self.generateCombinatio(candidates, target, i + 1, ans)
                    self.old = ans.pop()
                else:
                    continue



s = Solution()
can = [10,1,2,7,6,1,5]
tar = 8

s.combinationSum2(can,tar)