題目： 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.
思路：從左至右掃描亥啦，同時(shí)維護(hù)兩個(gè)指針，p1指向最左邊的0效五，p2指向p1右邊的第一個(gè)非0辑舷，將p1和p2的元素交換毁涉，如果p2不存在則說(shuō)明現(xiàn)在的序列已滿足要求莱衩。
代碼：
def moveZeroes(self, nums):
"""
:type nums: List[int]
:rtype: void Do not return anything, modify nums in-place instead.
"""
if nums==None or len(nums)==0:
return None
p1 = 0
while True:
while p1<len(nums) and nums[p1] != 0:
p1 += 1
p2 = p1 + 1
while p2<len(nums) and nums[p2]==0:
p2 += 1
if p2 >= len(nums):
break
else:
nums[p1],nums[p2] = nums[p2],nums[p1]
