RemoveDuplicatesFromSortedArray.py

# Source : https://leetcode.com/problems/remove-duplicates-from-sorted-array
# Author : Hamza Mogni
# Date   : 2022-06-01

##################################################################################################### 
#
# Given an integer array nums sorted in non-decreasing order, remove the duplicates in-place such 
# that each unique element appears only once. The relative order of the elements should be kept the 
# same.
# 
# Since it is impossible to change the length of the array in some languages, you must instead have 
# the result be placed in the first part of the array nums. More formally, if there are k elements 
# after removing the duplicates, then the first k elements of nums should hold the final result. It 
# does not matter what you leave beyond the first k elements.
# 
# Return k after placing the final result in the first k slots of nums.
# 
# Do not allocate extra space for another array. You must do this by modifying the input array 
# in-place with O(1) extra memory.
# 
# Custom Judge:
# 
# The judge will test your solution with the following code:
# 
# int[] nums = [...]; // Input array
# int[] expectedNums = [...]; // The expected answer with correct length
# 
# int k = removeDuplicates(nums); // Calls your implementation
# 
# assert k == expectedNums.length;
# for (int i = 0; i < k; i++) {
#     assert nums[i] == expectedNums[i];
# }
# 
# If all assertions pass, then your solution will be accepted.
# 
# Example 1:
# 
# Input: nums = [1,1,2]
# Output: 2, nums = [1,2,_]
# Explanation: Your function should return k = 2, with the first two elements of nums being 1 and 2 
# respectively.
# It does not matter what you leave beyond the returned k (hence they are underscores).
# 
# Example 2:
# 
# Input: nums = [0,0,1,1,1,2,2,3,3,4]
# Output: 5, nums = [0,1,2,3,4,_,_,_,_,_]
# Explanation: Your function should return k = 5, with the first five elements of nums being 0, 1, 2, 
# 3, and 4 respectively.
# It does not matter what you leave beyond the returned k (hence they are underscores).
# 
# Constraints:
# 
# 	1 <= nums.length <= 3 * 10^4
# 	-100 <= nums[i] <= 100
# 	nums is sorted in non-decreasing order.
#####################################################################################################

from typing import List

class Solution:
    def removeDuplicates(self, nums: List[int]) -> int:
        current = 0

        for last in range(len(nums)):
            if nums[last] > nums[current]:
                current += 1
                nums[current] = nums[last]
        
        return current + 1


s = Solution()
assert s.removeDuplicates([0,0,1,1,1,2,2,3,3,4]) == 5