26. Remove Duplicates from Sorted Array

Given a sorted array nums, remove the duplicates in-place such that each element appear only once and return the new length.

Do not allocate extra space for another array, you must do this by modifying the input array in-place with O(1) extra memory.

 3个指针，一个是当前不同值的位置，另外两个是当前值的左端点和右端点

class Solution(object):
    def removeDuplicates(self, nums):
        """
        :type nums: List[int]
        :rtype: int
        """
        n = len(nums)
        if n <= 1:
            return n
        index = 0
        l = 0
        r = 1
        while l < n and r < n:
            while r < n and nums[r] == nums[l]:
                r += 1
            nums[index] = nums[l]
            index += 1
            l = r
        return index