# Solving Leetcode Interviews in Seconds with AI: Transform Array by Parity


	# Introduction
	In this blog post, we will explore how to solve the LeetCode problem "3467" using AI. LeetCode is a popular platform for preparing for coding interviews, and with the help of AI tools like [Chatmagic](https://www.chatmagic.app), we can generate solutions quickly and efficiently - helping you pass the interviews and get the job offer without having to study for months.

	# Problem Statement
	> You are given an integer array nums. Transform nums by performing the following operations in the exact order specified:  Replace each even number with 0. Replace each odd numbers with 1. Sort the modified array in non-decreasing order.  Return the resulting array after performing these operations.   Example 1:  Input: nums = [4,3,2,1] Output: [0,0,1,1] Explanation:  Replace the even numbers (4 and 2) with 0 and the odd numbers (3 and 1) with 1. Now, nums = [0, 1, 0, 1]. After sorting nums in non-descending order, nums = [0, 0, 1, 1].   Example 2:  Input: nums = [1,5,1,4,2] Output: [0,0,1,1,1] Explanation:  Replace the even numbers (4 and 2) with 0 and the odd numbers (1, 5 and 1) with 1. Now, nums = [1, 1, 1, 0, 0]. After sorting nums in non-descending order, nums = [0, 0, 1, 1, 1].     Constraints:  1 <= nums.length <= 100 1 <= nums[i] <= 1000  

	# Explanation
	*   **In-place Transformation:** Iterate through the input array and replace even numbers with 0 and odd numbers with 1 directly within the original array.
*   **Counting Sort Optimization:** Instead of using a general-purpose sorting algorithm, leverage the fact that we only have two distinct values (0 and 1) to perform a counting sort. Count the occurrences of 0s and 1s.
*   **Reconstruction:** Rebuild the sorted array based on the counts of 0s and 1s.

*   **Runtime Complexity:** O(n), where n is the length of the input array. **Storage Complexity:** O(1) - constant extra space.

	
	# Code
	```python
	def transform_array(nums):
    """
    Transforms an array by replacing even numbers with 0, odd numbers with 1,
    and then sorting the modified array in non-decreasing order.

    Args:
        nums: A list of integers.

    Returns:
        A list of integers representing the transformed and sorted array.
    """

    zeros = 0
    ones = 0

    # Count the number of 0s and 1s after transformation.
    for i in range(len(nums)):
        if nums[i] % 2 == 0:
            nums[i] = 0
            zeros += 1
        else:
            nums[i] = 1
            ones += 1

    # Reconstruct the array with sorted 0s and 1s.
    for i in range(len(nums)):
        if i < zeros:
            nums[i] = 0
        else:
            nums[i] = 1

    return nums
	```