An array is given containing only 0s, 1s, and 2s. Sort the array in ascending order.

Write a function `solve`

that have the following parameter(s):

1.) *arr = array of integers*

**Example**

Input:

`arr = [2, 1, 0, 1]`

Output:

The function will return,

`[0, 1, 1, 2]`

Input:

`arr = [1, 0, 2, 1, 0, 2]`

Output:
`[0, 0, 1, 1, 2, 2]`

**Explanation**

After sorting an array in ascending order. 0s, 1s, and 2s are arranged.

**Constraints**

• The number of elements in the array will be greater than or equal to 1 and less than or equal to 1000.

• Each element of the array will be greater than or equal to 0 and less than or equal to 2.