Array consist of only 0's, 1's and 2's. Write an algorithm to sort this array in O(n) time complexity with only one traversal

**Example:**

Input : [0 1 2 0 1 2]

Modify array so that it becomes : [0 0 1 1 2 2] Constraint1 : You are not suppose to use any extra space Constraint2 : You need to change the same array with single traversal with O(n) time complexity

Problem level: **Easy**