Write a method named unflatten that accepts three parameters: a 1-D array of integers, and a number of rows and columns.
Your method should convert the 1-D array into a 2-D array with the given number of rows and columns, where values are transferred in row-major order into the two-dimensional array.
For example, if the given array is declared:
int[] a = {3, 8, 12, 2, 9, 17, 43, -8, 46, 203, 14, 97};
Then the call of unflatten(a, 4, 3) should return the following 2-D array:
{{ 3, 8, 12},
{ 2, 9, 17},
{ 43, -8, 46},
{203, 14, 97}}
The call of unflatten(a, 6, 2) should return the following 2-D array:
{{ 3, 8},
{ 12, 2},
{ 9 17},
{ 43, -8},
{ 46, 203},
{ 14, 97}}
If the array's contents do not fit exactly into a 2-D array of the given dimensions, your method should throw an IllegalArgumentException.
Your code should work for an array of any size.
Your method should not modify the array that is passed in.
