https://leetcode-cn.com/problems/remove-duplicates-from-sorted-array/
def removeDuplicates(nums):
""" 删除排序数组中的重复项 """
if not nums:
return 0
i = 0
j = i + 1
while j <= len(nums) - 1:
if nums[i] != nums[j]:
nums[i + 1] = nums[j]
i += 1
j += 1
return i + 1