class Solution { public int[][] construct2DArray(int[] original, int m, int n) { if (original.length != m * n) { return new int[0][0]; } var array = new int[m][n]; for (int i = 0; i < m * n; ++i) { int y = i / n, x = i % n; array[y][x] = original[i]; } return array; } }