SDE - 1

Approach : 
1) We will reverse both linked lists so that we can easily process the number in this manner.
2) Now, we will start adding the nodes of both linked lists and use another variable ‘carry’ to keep track of the carry generated in each addition. 
3) We will be updating either of the linked lists to their sum. Hence, we will not be using any extra space for storing the result.
4) In the end, if we are left with a ‘carry’ greater than 0, we will just add a new node in our resultant linked list.

TC : O(N+M), where ‘N’ and ‘M’ are the numbers of nodes in both linked lists. 
SC : O(1)

Approach :
For each node, first the node is visited and then it’s child nodes are put in a queue. 
Steps :
printLevelorder(tree)
1) Create an empty queue q
2) temp_node = root 
3) Loop while temp_node is not NULL
a) print temp_node->data.
b) Enqueue temp_node’s children 
(first left then right children) to q
c) Dequeue a node from q.

TC : O(N) , where N is the number of nodes in the binary tree 
SC : O(N)

If there are two or more functions with the same name defined in different libraries then how will the compiler know which one to refer to? Thus namespace came to picture. A namespace defines a scope and differentiates functions, classes, variables etc. with the same name available in different libraries. The namespace starts with the keyword “namespace”. The syntax for the same is as follows:

namespace namespace_name {
// code declarations
}

Storage class in C++ specifically resemble life or even the scope of symbols, including the variables, functions, etc. Some of the storage class names in C++ include mutable, auto, static, extern, register, etc.

Sometimes, there is a need for allowing a particular class to access private or protected members of a class. The solution is a friend class, which can access the protected and private members of the class in which it is declared as a friend.

Similar to the friend class, a friend function is able to access private and protected class members. A friend function can either be a global function or a method of some class.

Some important points about friend class and friend function:

1) Friendship is not inherited.

2) Friendship isn’t mutual, i.e., if some class called Friend is a friend of some other class called NotAFriend, then it doesn’t automatically become a friend of the Friend class.

3) The total number of friend classes and friend functions should be limited in a program as the overabundance of the same might lead to a depreciation of the concept of encapsulation of separate classes, which is an inherent and desirable quality of object-oriented programming.

Denoted by the static keyword, a static member is allocated storage, in the static storage area, only once during the program lifetime. Some important facts pertaining to the static members are:

i) Any static member function can’t be virtual.
ii) Static member functions don’t have ‘this’ pointer.
iii) The const, const volatile, and volatile declaration aren’t available for static member functions

Approach :
1) We will maintain two stacks, one for each direction i.e. leftToRight and rightToleft.
2) We will do a level order traversal of the given binary tree and push nodes of each level onto one of the stack according to the current direction of traversal.
3) After we’ve pushed all nodes of a level onto one stack, we’ll start popping those nodes. While popping the nodes we will push their children (if any) onto our other direction stack, so that the next level be traversed in reverse order.

TC : O(N), where ‘N’ is the number of nodes in the binary tree.
SC : O(N)

Open System Interconnections (OSI) is a network architecture model based on the ISO standards. It is called the OSI model as it deals with connecting the systems that are open for communication with other systems.

The OSI model has seven layers. The principles used to arrive at the seven layers can be summarized briefly as below:

1) Create a new layer if a different abstraction is needed.
2) Each layer should have a well-defined function.
3) The function of each layer is chosen based on internationally standardized protocols.

The router is a networking device used for connecting two or more network segments. It directs the traffic in the network. It transfers information and data like web pages, emails, images, videos, etc. from source to destination in the form of packets. It operates at the network layer. The gateways are also used to route and regulate the network traffic but, they can also send data between two dissimilar networks while a router can only send data to similar networks.

Steps :
Let's call 5L jar as X and 3L jar as Y.
1) We'll take the first jar, i.e, X. Fill X completely.
2) Then empty the X content in Y. We are left with 2 L in the X.
3) Now we will empty the Y jar and then Fill 2L from X into Y. We are left with 0L in X and 2L in Y.
4) Now again we will fill X with 5L and then empty till Y gets full.
5) As Y is already full with 2L from previous operation so it can only accomodate 1L now from X. So when
Y jar is full automatically we will have 4L left in X. This is how we will calculate 4L