Convert 1D Array Into 2D Array

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.

LeetCode Problem - 2022

class Solution {
    // Method to convert a 1D array (original) into a 2D array with m rows and n columns
    public int[][] construct2DArray(int[] original, int m, int n) {
        // Check if the total number of elements matches m * n
        // If not, return an empty 2D array
        if (m * n == original.length) {
            // Create the 2D array to store the result
            int[][] answer = new int[m][n];

            // Index to keep track of the position in the original 1D array
            int idx = 0;

            // Fill the 2D array with elements from the original array
            for (int i = 0; i < m; i++) {
                for (int j = 0; j < n; j++) {
                    // Assign elements from the original array to the 2D array
                    answer[i][j] = original[idx];
                    idx++;  // Move to the next element in the 1D array
                }
            }
            // Return the constructed 2D array
            return answer;
        } else {
            // If the number of elements doesn't match, return an empty 2D array
            return new int[0][0];
        }
    }
}