main.py

# Source: https://leetcode.com/problems/remove-duplicates-from-sorted-array
# Title: Remove Duplicates from Sorted Array
# Difficulty: Easy
# Author: Mu Yang <http://muyang.pro>

################################################################################################################################
# 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**. Then return the number of unique elements in `nums`.
#
# Consider the number of unique elements of `nums` to be `k`, to get accepted, you need to do the following things:
#
# - Change the array `nums` such that the first `k` elements of `nums` contain the unique elements in the order they were present in `nums` initially. The remaining elements of `nums` are not important as well as the size of `nums`.
# - Return `k`.
#
# **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:
        n = len(nums)

        dstIdx = 1
        for srcIdx in range(1, n):
            if nums[srcIdx] != nums[srcIdx - 1]:
                nums[dstIdx] = nums[srcIdx]
                dstIdx += 1

        return dstIdx