Day 4: Move Zeroes.py

import unittest
# Day 4: Move Zeroes
#
# 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.
#
# Example:
#
# Input: [0,1,0,3,12]
# Output: [1,3,12,0,0]

class unitest(unittest.TestCase):
    def testEmptylist(self):
        input = []
        output = []
        self.assertEqual(Solution().moveZeroes(input),output)
    def test(self):
        input = [1, 0, 0, 3, 11, 55]
        output = [1, 3, 11, 55, 0, 0]
        self.assertEqual(Solution().moveZeroes(input),output)
    def testZero(self):
        input = [0, 0, 1]
        output = [1, 0, 0]
        self.assertEqual(Solution().moveZeroes(input), output)
        

class Solution(object):
    def moveZeroes(self, nums):
        """
        :type nums: List[int]
        :rtype: None Do not return anything, modify nums in-place instead.
        """
        # Counter for not zero elements 
        count_elem = 0
        for i in range(len(nums)):
            if nums[i] != 0:
                nums[i], nums[count_elem] = nums[count_elem], nums[i]   # swap the positions of the elements
                count_elem += 1
        return nums


if __name__ == '__main__':
    unittest.main()