1. Array

Definition

An Array is a linear data structure that stores elements of the same type in contiguous memory locations.

Characteristics

• Fixed size
• Fast access using index (O(1))
• Homogeneous elements
• Insertion/deletion is costly

Real-Life Example

• Storing marks of students in a list

Best For (Key Insight)

• When fast access to elements is required
• When data size is known in advance

2. Linked List

Definition

A Linked List is a linear data structure consisting of nodes, where each node contains data and a pointer to the next node.

Characteristics

• Dynamic size
• Non-contiguous memory
• Sequential access
• Efficient insertion/deletion

Real-Life Example

• Music playlist navigation

Best For (Key Insight)

• When frequent insertion/deletion is needed

3. Stack

Definition

A Stack is a linear data structure that follows the LIFO (Last In, First Out) principle.

Characteristics

• Operations: Push, Pop, Peek
• Access from one end (top)
• Fast operations (O(1))

Real-Life Example

• Stack of plates

Best For (Key Insight)

• Undo operations, recursion, expression evaluation

4. Queue

Definition

A Queue is a linear data structure that follows the FIFO (First In, First Out) principle.

Characteristics

• Two ends: Front and Rear
• Operations: Enqueue, Dequeue
• Ordered processing

Real-Life Example

• People standing in a line

Best For (Key Insight)

• Scheduling, buffering, task processing

5. Tree

Definition

A Tree is a non-linear hierarchical data structure consisting of nodes connected by edges.

Characteristics

• Root node
• Parent-child relationship
• No cycles
• Recursive structure

Real-Life Example

• File system folders

Best For (Key Insight)

• Representing hierarchical data

6. Graph

Definition

A Graph is a non-linear data structure consisting of vertices (nodes) and edges connecting them.

Characteristics

• Directed/Undirected
• Weighted/Unweighted
• Can contain cycles

Real-Life Example

• Social networks

Best For (Key Insight)

• Representing relationships and networks

7. Heap

Definition

A Heap is a complete binary tree that satisfies the heap property.

Characteristics

• Complete binary tree
• Parent-child ordering
• Efficient priority operations

Real-Life Example

• Priority queue (task scheduling)

Best For (Key Insight)

• Priority-based processing

8. Hash Table

Definition

A Hash Table is a data structure that stores data in key-value pairs using a hash function.

Characteristics

• Fast access (O(1) average)
• Uses hashing
• Handles collisions

Real-Life Example

• Dictionary (word → meaning)

Best For (Key Insight)

• Fast searching and lookup

9. Trie

Definition

A Trie is a tree-like data structure used to store strings where each node represents a character.

Characteristics

• Prefix-based storage
• Fast string searching
• Memory-intensive

Real-Life Example

• Autocomplete systems

Best For (Key Insight)

• Prefix searching and dictionary problems

10. Deque

Definition

A Deque is a data structure in which insertion and deletion can occur at both ends.

Characteristics

• Flexible (stack + queue)
• Operations at both ends
• Efficient (O(1))

Real-Life Example

• Sliding window problems

Best For (Key Insight)

• When both-end operations are required

Summary

• Array → Fast access
• Linked List → Flexible memory
• Stack → Reversal / recursion
• Queue → Order processing
• Tree → Hierarchy
• Graph → Relationships
• Heap → Priority
• Hash Table → Fast lookup
• Trie → Strings/prefixes
• Deque → Dual operations