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