leetcode_gym/_problems/removeDupFromSortedArray.md

layout, title, last_solved, category, leetcode_url, status

layout	title	last_solved	category	leetcode_url	status
page	Remove Duplicate from Sorted Array	2020-06-03	array, 2ptr	https://leetcode.com/problems/remove-duplicates-from-sorted-array	Solved

Problem

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.

Example 1:

Given nums = [1,1,2],

Your function should return length = 2, with the first two elements of nums being 1 and 2 respectively.

It doesn't matter what you leave beyond the returned length.
Example 2:

Given nums = [0,0,1,1,1,2,2,3,3,4],

Your function should return length = 5, with the first five elements of nums being modified to 0, 1, 2, 3, and 4 respectively.

It doesn't matter what values are set beyond the returned length.

Solution

{% highlight python %}

def removeDuplicates(self, nums: List[int]) -> int:

if not nums: return 0

# [1,1,2]
# [0,0,1,1,1,2,2,3,3,4],

slow, fast = 0, 0

while fast<len(nums):
    
    # move fast until different num 
    if nums[fast]==nums[slow]:
        fast+=1
    else:
        slow+=1
        nums[slow]=nums[fast]

    #print(slow, fast, nums)
        
return slow+1

{% endhighlight %}