26. Remove Duplicates from Sorted Array LeetCode Solution

In this guide we will provide 26. Remove Duplicates from Sorted Array LeetCode Solution with best time and space complexity. The solution to Remove Duplicates from Sorted Array problem is provided in various programming languages like C++, Java and python. This will be helpful for you if you are preparing for placements, hackathon, interviews or practice purposes. The solutions provided here are very easy to follow and with detailed explanations.

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26. Remove Duplicates from Sorted Array LeetCode Solution image

Problem Statement of Remove Duplicates from Sorted Array

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];
}

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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 * 104
-100 <= nums[i] <= 100
nums is sorted in non-decreasing order.

Complexity Analysis

  • Time Complexity: O(n)
  • Space Complexity: O(n)

26. Remove Duplicates from Sorted Array LeetCode Solution in C++

class Solution {
 public:
  int removeDuplicates(vector<int>& nums) {
    int i = 0;

    for (const int num : nums)
      if (i < 1 || num > nums[i - 1])
        nums[i++] = num;

    return i;
  }
};
/* code provided by PROGIEZ */

26. Remove Duplicates from Sorted Array LeetCode Solution in Java

class Solution {
  public int removeDuplicates(int[] nums) {
    int i = 0;

    for (final int num : nums)
      if (i < 1 || num > nums[i - 1])
        nums[i++] = num;

    return i;
  }
}
// code provided by PROGIEZ

26. Remove Duplicates from Sorted Array LeetCode Solution in Python

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

    for num in nums:
      if i < 1 or num > nums[i - 1]:
        nums[i] = num
        i += 1

    return i
#code by PROGIEZ

Additional Resources

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