https://leetcode-cn.com/problems/remove-duplicates-from-sorted-array/ (opens new window) 需要注意的点

class Solution(object):
    def removeDuplicates(self, nums):
        """
        :type nums: List[int]
        :rtype: int
        """
        if len(nums) < 1:
            return 0
        slow = 0 
        fast = 0
        while fast < len(nums):
            if nums[slow] != nums[fast]:
                # 符合条件 slow增加, 条件是 slow 跟fast相等
                slow += 1
                nums[slow] = nums[fast]
                
            # fast 总是增加
            fast += 1
        return slow+1