Introduction

In this blog post, we will explore how to solve the LeetCode problem "2022" using AI. LeetCode is a popular platform for preparing for coding interviews, and with the help of AI tools like Chatmagic, 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 a 0-indexed 1-dimensional (1D) integer array original, and two integers, m and n. You are tasked with creating a 2-dimensional (2D) array with m rows and n columns using all the elements from original. The elements from indices 0 to n - 1 (inclusive) of original should form the first row of the constructed 2D array, the elements from indices n to 2 n - 1 (inclusive) should form the second row of the constructed 2D array, and so on. Return an m x n 2D array constructed according to the above procedure, or an empty 2D array if it is impossible. Example 1: Input: original = [1,2,3,4], m = 2, n = 2 Output: [[1,2],[3,4]] Explanation: The constructed 2D array should contain 2 rows and 2 columns. The first group of n=2 elements in original, [1,2], becomes the first row in the constructed 2D array. The second group of n=2 elements in original, [3,4], becomes the second row in the constructed 2D array. Example 2: Input: original = [1,2,3], m = 1, n = 3 Output: [[1,2,3]] Explanation: The constructed 2D array should contain 1 row and 3 columns. Put all three elements in original into the first row of the constructed 2D array. Example 3: Input: original = [1,2], m = 1, n = 1 Output: [] Explanation: There are 2 elements in original. It is impossible to fit 2 elements in a 1x1 2D array, so return an empty 2D array. Constraints: 1 <= original.length <= 5 104 1 <= original[i] <= 105 1 <= m, n <= 4 * 104

Explanation

Here's an efficient solution to the problem:

• Check feasibility: Verify if the product of m and n equals the length of the original array. If not, return an empty list.
• Reshape: Create the 2D array and populate it by iterating through the original array and placing elements into the correct row and column based on the row and column indices.

• Return result: Return the new 2D array.

• Runtime Complexity: O(m*n), where m is the number of rows and n is the number of columns.

• Storage Complexity: O(m*n) to store the reshaped 2D array.

Code

    def construct2DArray(original, m, n):
    """
    Constructs a 2D array from a 1D array.

    Args:
        original (list): The 1D integer array.
        m (int): The number of rows in the 2D array.
        n (int): The number of columns in the 2D array.

    Returns:
        list: The constructed 2D array, or an empty list if impossible.
    """
    if m * n != len(original):
        return []

    result = [[0] * n for _ in range(m)]
    for i in range(m):
        for j in range(n):
            result[i][j] = original[i * n + j]

    return result