shuffle-an-array.py

# V0

# V1 
# http://bookshadow.com/weblog/2016/08/12/leetcode-shuffle-array/
import random
class Solution(object):

    def __init__(self, nums):
        """
        
        :type nums: List[int]
        :type size: int
        """
        self.nums = nums[:]
        self.base = nums[:]

    def reset(self):
        """
        Resets the array to its original configuration and return it.
        :rtype: List[int]
        """
        self.nums[:] = self.base
        return self.nums

    def shuffle(self):
        """
        Returns a random shuffling of the array.
        :rtype: List[int]
        """
        for x in range(len(self.nums)):
            y = random.randint(0, x)
            self.nums[x], self.nums[y] = self.nums[y], self.nums[x] # simulate the "manual card shuffle" process
        return self.nums
# Your Solution object will be instantiated and called as such:
# obj = Solution(nums)
# param_1 = obj.reset()
# param_2 = obj.shuffle()


# V1'
# https://blog.csdn.net/fuxuemingzhu/article/details/79391342
import random
class Solution(object):

    def __init__(self, nums):
        """
        :type nums: List[int]
        """
        self.nums = nums

    def reset(self):
        """
        Resets the array to its original configuration and return it.
        :rtype: List[int]
        """
        return self.nums

    def shuffle(self):
        """
        Returns a random shuffling of the array.
        :rtype: List[int]
        """
        nums_s = self.nums[:]
        random.shuffle(nums_s)
        return nums_s
        
# V2
# Time:  O(n)
# Space: O(n)
import random
class Solution(object):

    def __init__(self, nums):
        """
        :type nums: List[int]
        :type size: int
        """
        self.__nums = nums


    def reset(self):
        """
        Resets the array to its original configuration and return it.
        :rtype: List[int]
        """
        return self.__nums


    def shuffle(self):
        """
        Returns a random shuffling of the array.
        :rtype: List[int]
        """
        nums = list(self.__nums)
        for i in range(len(nums)):
            j = random.randint(i, len(nums)-1)
            nums[i], nums[j] = nums[j], nums[i]
        return nums