递归和回溯_leetcode46-经典的排列问题

class Solution(object):
    def permute(self, nums):
        """
 :type nums: List[int]
 :rtype: List[List[int]]
 """
 pass

 self.res =[]

 length = len(nums)

 self.used = [False for i in range(length)]

 self.generatePermutation(nums,0,[])

 # print self.res

 return self.res



 # visit[] 用于分支去重
 def generatePermutation(self,nums,index,p):


 if index == len(nums):

 self.res.append(p[0:])
 return


 for i in range(len(nums)):
 if not self.used[i]:

 p.append(nums[i])
 self.used[i] = True
 self.generatePermutation(nums,index+1,p)
 self.used[i] = False
 p.pop()



s = Solution()

n = [1,2,3]

s.permute(n)