# Sort an array of 0s, 1s and 2s – Simple Counting Sort Solution ### Sort an array approach :

Programming fundamentals include sorting an array, and Java provides a variety of techniques for doing so. We’ll look at how to sort an array in Java in this blog.

When you sort an array, you put the items in a particular order, such as ascending or descending. This can be useful in a lot of situations, such as when you need to quickly locate a certain element in the array or when you want to display the items in a particular order.

The sort() method of the Arrays class is one of the built-in sorting methods offered by Java for arrays. An array of primitive data types, such as int, long, and double, are sorted using the Dual-Pivot Quicksort algorithm via the sort() method, while an array of objects is sorted using the merge sort algorithm.

### Example :

Here’s an example of how to sort an array of integers in ascending order using the sort() method of the Arrays class:

``````import java.util.Arrays;

int[] arr = {3, 60, 35, 2, 45, 320, 5};

Arrays.sort(arr);

for (int i : arr) {
System.out.print(i + " ");
}
``````

In the above code, we first import the Arrays class, then we create an array of integers called arr. Next, we call the sort() method of the Arrays class on the array and finally, we use a for-each loop to print the sorted array.

### Question from GeeksForGeeks :

#### Given an array of size N containing only 0s, 1s, and 2s; sort the array in ascending order.

Example 1:

```Input:
N = 5
arr[]= {0 2 1 2 0}
Output:
0 0 1 2 2
Explanation:
0s 1s and 2s are segregated
into ascending order.```

Example 2:

```Input:
N = 3
arr[] = {0 1 0}
Output:
0 0 1

Explanation:
0s 1s and 2s are segregated
into ascending order.

You don't need to read input or print anything. Your task is to complete the function sort012() that takes an array arr and N as input parameters and sorts the array in-place.

Expected Time Complexity: O(N)
Expected Auxiliary Space: O(1)

Constraints:
1 <= N <= 10^6
0 <= A[i] <= 2

```

### Solution using predefined function :

``````//Solution by technoname.com

class Solution
{
public static void sort012(int a[], int n)
{
Arrays.sort(a);
}
}``````

### Solution using Bubble sort algorithm :

``````class Solution
{
public static void sort012(int a[], int n)
{
int i ,j,temp=0;
for(i=0;i<n;i++){
for(j=0;j<n;j++){
if(a[i]<a[j]){
temp=a[i];
a[i]=a[j];
a[j]=temp;
}
}
}
}
}``````