2022.1.1-----leetcode.2022

 public int[][] construct2DArray(int[] original, int m, int n) {
        int[][] array=new int[m][n];
        if(original.length!=m*n)
            return new int[0][];
        int k=0;
        for (int i = 0; i < m; i++) {
            for (int j = 0; j < n; j++) {
                array[i][j]=original[k++];

            }

        }
        return array;

    }