find 0, pop it out and add 0 in the end

```
class Solution(object):
def moveZeroes(self, nums):
if not nums: return
length = len(nums)
i = length-1
j = 0
while i >= 0:
if nums[j] == 0:
nums.pop(j)
nums.append(0)
else:
j += 1
i -= 1
```