Stack
A linear data structure that follows the LIFO principle
Stack
A stack is a linear data structure that follows the Last In, First Out (LIFO) principle. Think of it like a stack of plates - you can only add or remove plates from the top.
Core Concept
LIFO Principle: The last element added to the stack will be the first one to be removed.
Real-world Example: Imagine stacking plates in a cafeteria. When you add a plate, you place it on top. To remove a plate, you take the topmost one first.
Key Properties
Linear Structure
Elements are arranged sequentially, with each element connected to adjacent ones.
Single Access Point
All operations happen at the 'top' of the stack. No direct access to middle or bottom elements.
LIFO Operations
Last element inserted is the first to be removed, ensuring ordered access.
Dynamic Size
Can be implemented with fixed arrays or dynamic linked lists.
Types of Stack Implementation
Fixed Size Stack
Array-based implementation with predetermined maximum capacity.
Characteristics:
- Size defined at creation time
- Cannot exceed predefined capacity
- Memory allocated upfront
Advantages:
- Simple to implement
- Efficient when maximum size is known
- Fast access due to contiguous memory
Disadvantages:
- Memory wastage if not fully utilized
- Stack overflow if capacity exceeded
- Difficult to resize dynamically
Dynamic Size Stack
Linked list-based implementation that grows and shrinks as needed.
Characteristics:
- Grows/shrinks based on usage
- Memory allocated on demand
- No predefined size limit
Advantages:
- No memory wastage
- Handles unexpected growth
- Flexible size management
Disadvantages:
- Slightly more complex implementation
- Additional memory overhead for pointers
- Non-contiguous memory allocation
Learning Path
Understand LIFO Principle - Master the core concept with real-world examples
Learn Basic Operations - Study push, pop, peek, and isEmpty operations
Compare Implementations - Understand array vs linked list trade-offs
Practice Applications - Explore use cases like expression evaluation and function calls
Next Steps
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