A Stack is a fundamental linear data structure that operates on the Last In, First Out (LIFO) principle, making it an essential tool in computer science and software development. This powerful data structure is widely used in various applications, from managing function calls in programming languages to implementing undo/redo features in software applications.
Core Characteristics
- Follows the LIFO principle - Last element added is the first to be removed
- Maintains a single point of access (the top of the stack)
- Provides constant-time operations for basic functions
- Ideal for managing nested operations and recursive algorithms
Key Operations
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Push() This operation adds a new element to the top of the stack. The newly added element becomes the new top, while the previous top element moves down one position. This operation is crucial for building the stack and maintaining its LIFO property. Complexity: O(1) - Constant time operation
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Pop() This operation removes and returns the top element of the stack. Following the LIFO principle, it always removes the most recently added element. This operation is essential for processing elements in reverse order of their addition. Complexity: O(1) - Constant time operation
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Peek() This operation inspects the top element without removing it. It's particularly useful for checking the current state of the stack without modifying its contents, making it ideal for conditional operations and stack state validation. Complexity: O(1) - Constant time operation
Common Applications
- Function call management in programming languages
- Expression evaluation and syntax parsing
- Undo/redo operations in software applications
- Browser history management
- Memory management in operating systems