MoveZeroes.py

'''
Given an array nums, write a function to move all 0's to the end of it while maintaining the relative order of the non-zero elements.

For example, given nums = [0, 1, 0, 3, 12], after calling your function, nums should be [1, 3, 12, 0, 0].

Note:
    You must do this in-place without making a copy of the array.
    Minimize the total number of operations.
'''
class Solution(object):
    def moveZeroes(self, nums):
        l = len(nums)
        if l<2:
            return
        i,j = 0,1
        while j<l:
            if not nums[i] and nums[j]:
                nums[i] = nums[j]
                nums[j] = 0
                i+=1
                j+=1
            elif not nums[i] and not nums[j]:
                j+=1
            else:
                i+=1
                j+=1



s = Solution()
example0 = []
example1 = [1,0,1,0,2,4]
example2 = [0,6,0,4,5,4,5,6,0]
s.moveZeroes(example0)
s.moveZeroes(example1)
s.moveZeroes(example2)
assert [] == example0
assert [1,1,2,4,0,0] == example1
assert [6,4,5,4,5,6,0,0,0] == example2