Mastering Data Structures

What is the main difference between an array and a linked list?

• Arrays consist of nodes linked by pointers, while linked lists do not.

• Linked lists allow index-based access while arrays do not.

• Arrays can grow dynamically while linked lists have fixed sizes.

• The main difference is that arrays have fixed sizes and allow index-based access, while linked lists are dynamic and consist of nodes linked by pointers.

How do you insert an element at the beginning of a linked list?

• Remove the last element and add the new one at the end.

• Create a new node, set its next to the current head, and update the head to the new node.

• Insert the new node in the middle of the list.

• Replace the current head with the new node without linking.

What is the time complexity of accessing an element in an array?

• O(n^2)

• O(1)

• O(n)

• O(log n)

Explain the concept of a stack and its main operations.

• A stack is a LIFO data structure with main operations: push (add), pop (remove), and peek (view top).

• A stack is a FIFO data structure with operations: enqueue (add), dequeue (remove), and front (view front).

• A stack allows random access to elements and has operations: insert (add), delete (remove), and top (view top).

• A stack is a linear data structure with operations: add (push), remove (pop), and size (get size).

What is the difference between a stack and a queue?

• A stack can only hold integers, while a queue can hold any data type.

• A stack uses LIFO, while a queue uses FIFO.

• Both stack and queue use LIFO.

• A stack uses FIFO, while a queue uses LIFO.

How do you implement a queue using two stacks?

• Use two stacks: one for enqueueing and one for dequeueing. Transfer elements from the first stack to the second when needed.

• Use three stacks to manage the queue operations.

• Use a single stack for both enqueueing and dequeueing.

• Implement a queue using an array only.

What is a binary tree and how does it differ from a binary search tree?

• A binary tree is a type of graph; a binary search tree is a linear structure.

• A binary tree is always balanced; a binary search tree can be unbalanced.

• A binary tree is a tree structure with nodes having at most two children; a binary search tree is a binary tree with ordered nodes.

• A binary tree can have any number of children; a binary search tree can have only one.

What traversal methods can be used on trees?

• Level-order Traversal

• Random Access Traversal

• Circular Traversal

• Depth-First Search (DFS) and Breadth-First Search (BFS) including Pre-order, In-order, Post-order for DFS.

Define a graph and its components.

• A graph is defined by its components: lines and angles.

• A graph is a collection of colors and shapes.

• A graph is defined by its components: vertices (nodes) and edges (connections between nodes).

• A graph consists of only edges without any nodes.

What is the difference between directed and undirected graphs?

• Directed graphs have directed edges; undirected graphs have undirected edges.

• Directed graphs can have cycles; undirected graphs cannot.

• Directed graphs are used for trees; undirected graphs are used for networks.

• Directed graphs are always weighted; undirected graphs are not.