Convert 1D Array Into 2D Array

Problem Description

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.

Key Insights

• To form a valid 2D array, the total number of elements in original must equal m * n.
• If the length of original is not equal to m * n, it is impossible to fill the array, and we should return an empty array.
• The 2D array can be constructed by iterating through original and filling each row based on the calculated indices.

Space and Time Complexity

Time Complexity: O(m * n)
Space Complexity: O(m * n)

Solution

To solve this problem, we will:

1. Check if the length of the original array is equal to m * n. If not, return an empty array.
2. Initialize a 2D array with m rows.
3. Use a loop to fill each row by slicing the original array into segments of size n.
4. Return the constructed 2D array.

The key data structure used here is a 2D array (list of lists) to hold the final result.

Code Solutions