Software Engineer

Global Variables
The variables declared outside any function are called global variables. They are not limited to any function. Any function can access and modify global variables. Global variables are automatically initialized to 0 at the time of declaration. Global variables are generally written before main() function.

Local Variables 
The variables which are declared inside the function, compound statement (or block) are called Local variables.

Static variables
A Static variable is able to retain its value between different function calls. The static variable is only initialized once, if it is not initialized, then it is automatically initialized to 0. Here is how to declare a static variable.

1. A variable or a function can be declared any number of times. A variable or a function can be defined only once
2. Memory will not be allocated during declaration. Memory will be allocated in definition.
3. int f(int);
The above is a function declaration. This declaration is just for informing the compiler that a function named f with return type and argument as int will be used in the function.
int f(int a)
{
      return a;
} 
The system allocates memory by seeing the above function definition.

The simple approach is to simply count the number of 0’s, 1’s, and 2’s. Then, place all 0’s at the beginning of the array followed by 1’s and 2's. The time complexity of this approach would be O(n) and space complexity O(1). 

However, the approach requires two traversals of the array. The question can also be solved in a single scan of the array by maintaining the correct order of 0’s, 1’s, and 2’s using variables. 

We divide the array into four groups using three pointers. Let us name these pointers as low, mid, and high.
1. a[0…low-1] only zeroes
2. a[low..mid-1] only ones
3. a[mid…high] unknown
4. a[high+1..n-1] only twos

Algorithm : 
1. Initialise three pointers low = 0, mid = 0 and high = n -1
2. Run a while loop until mid<=high : 
2.1 If (a[mid] ==0), then swap the element with the element low and increment low and mid (low++ and mid++).
2.2 If (a[mid] ==1), then increment mid (mid++).
2.3 If (a[mid] ==2), then swap it with an element in high range and decrement high (high--).

Floyd's algorithm can be used to solve this question.
Define two pointers slow and fast. Both point to the head node, fast is twice as fast as slow. There will be no cycle if it reaches the end. Otherwise, it will eventually catch up to the slow pointer somewhere in the cycle.

Let X be the distance from the first node to the node where the cycle begins, and let X+Y be the distance the slow pointer travels. To catch up, the fast pointer must travel 2X + 2Y. L is the cycle size. The total distance that the fast pointer has travelled over the slow pointer at the meeting point is what we call the full cycle.
X+Y+L = 2X+2Y
L=X+Y
Based on our calculation, slow pointer had already traveled one full cycle when it met fast pointer, and since it had originally travelled A before the cycle began, it had to travel A to reach the cycle's beginning! 
After the two pointers meet, fast pointer can be made to point to head. And both slow and fast pointers are moved till they meet at a node. The node at which both the pointers meet is the beginning of the loop.
 

Pseudocode :
 

detectCycle(Node *head) 
{
	Node *slow=head,*fast=head;

	while(slow!=NULL && fast!=NULL && fast->next!=NULL) 
	{

		slow = slow->next; 
		fast = fast->next->next; 

		if(slow==fast) 
		{
			fast = head;
			while(slow!=fast) 
			{

				slow = slow->next;
				fast=fast->next;
			}
			return slow;

		}

	}

	return NULL; 
}

Nondeterminism means a process that can have more than one result even when its input is fixed. In the real world, we often view things as non-deterministic because there are inputs that we cannot control.
for eg. If you throw a coin with the same motion and strength, it is unlikely to get the same result (Heads or Tails) every time.
Talking about real life examples of Non-Deterministic Automata; games such as Tic Tac Toe, Ludo, Playing Cards etc. all follow NDA approach in some or the other manner.

Tip 1 : The cross questioning can go intense some time, think before you speak.

Tip 2 : Be open minded and answer whatever you are thinking, in these rounds I feel it is important to have opinion.

Tip 3 : Context of questions can be switched, pay attention to the details. It is okay to ask questions in these round, like what are the projects currently the company is investing, which team you are mentoring. How all is the work environment etc.