Wiggle Sort — Python

# Time:  O(n)
# Space: O(1)

class Solution(object):
    def wiggleSort(self, nums):
        """
        :type nums: List[int]
        :rtype: void Do not return anything, modify nums in-place instead.
        """
        for i in xrange(1, len(nums)):
            if ((i % 2) and nums[i - 1] > nums[i]) or \
                (not (i % 2) and nums[i - 1] < nums[i]):
                # Swap unordered elements.
                nums[i - 1], nums[i] = nums[i], nums[i - 1]


# time: O(nlogn)
# space: O(n)
class Solution2(object):
    def wiggleSort(self, nums):
        """
        :type nums: List[int]
        :rtype: void Do not return anything, modify nums in-place instead.
        """
        nums.sort()
        med = (len(nums) - 1) // 2
        nums[::2], nums[1::2] = nums[med::-1], nums[:med:-1]