026 Remove duplicates from sorted array

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Original description:
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.

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• 要求： 给一个有序数组，除去重复元素。使得该数组中每个元素仅出现一次。
  • inplace, with O(1) extra memory.

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• 返回： 处理后数组的长度

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• 例子：
  • input: [1,1,2]
  • output: 2

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Solution

使用P1,P2一前一后从左往右，如果P2所指的元素与P1所指元素相同，从数组中POP P2所指元素。

class Solution(object):
    def removeDuplicates(self, nums):
        """
        :type nums: List[int]
        :rtype: int
        """
        if nums == []:
            return 0
        elif len(nums) == 1:
            return 1
        else:    
            p1 = 0
            p2 = 1
            while p2<len(nums):
                if nums[p2] == nums[p1]:
                    nums.pop(p2)
                else:
                    p1+=1
                    p2+=1
            return len(nums)