The article highlighted term “Stack”, explores importance of Stack, advantages & disadvantages of Stack, operations of Stack, Basic terms of Stack and Application of Stack etc. Learn about the stack data structure, its properties, and common operations such as push and pop. Discover how stacks are used in algorithms and applications.
Table of Contents
Stack
A Stack is the kind of data structure that stores data and allows to add and remove the data. The data is added one by one and the last time added data (i.e., the top level of data) is called Stack. It is also called LIFO (Last In First Out) which means the last data added to the stack will be the first data removed from it.
In other words,
Stack is the collection of data elements kept one by one at the top; the last or topmost element is called Stack. This means the last added element to the Stack will be removed first. Therefore Stack is also called LIFO, which means Last In Fast Out.
Examples:
Books arranged alphabetically.
Plates in the Kitchen.
Operations of a Stack
Push: Add an element to the top of the Stack.
Pop: Remove the top element from the Stack.
Peek: Get the value of the top element without removing it.
Size: Get the number of elements in the Stack.
isEmpty: Check if the Stack is empty.
isFull: Check if the Stack is full or exceed limit.
Stacks can be implemented using arrays or linked lists. Arrays are more efficient for accessing elements in the middle of the stack, while linked lists are more efficient for adding or removing elements from the beginning of the stack.
Stack’s Basic Characteristics
The essential characteristics of a stack data structure are:
- LIFO (Last In First Out): The last element added to the Stack is the first to be removed. This means that elements are removed from the top of the Stack in the reverse order in which they were added.
- Push operation: It adds an element to the top of the Stack. The new element becomes the top element of the Stack.
- Pop operation: It removes the top element from the Stack. After removing the top element, the next element on the Stack becomes the new top element.
- Peek operation: It is used to get the value of the top element of the Stack without removing it.
- Stack overflow: This occurs when a push operation is performed on a full stack. This means there is no more space to add new elements in the Stack.
- Stack underflow: This occurs when a pop operation is performed on an empty stack. This means that there are no elements in the Stack to remove.
- Fixed or dynamic size: A stack can have a fixed size, which means the maximum number of elements that can be added to the Stack is predetermined. Alternatively, it can have a dynamic size, meaning it can grow or shrink as elements are added or removed.
- Implementation: Stacks can be implemented using arrays, linked lists, or other data structures.
Stack’s Applications
Stacks are used in a variety of applications, including:
- Expression evaluation: Stacks are commonly used in programming languages to evaluate expressions. The expression is parsed and converted into postfix notation, and then a stack is used to evaluate the expression.
- Function call management: Stacks are used to manage function calls in programming languages. When a function is called, its parameters and return address are pushed onto the stack, and when the function returns, the parameters, and return address are popped off the stack.
- Backtracking algorithms: Stacks are used in backtracking algorithms to keep track of the path taken by the algorithm. When a dead end is reached, the algorithm backtracks by popping elements off the stack.
- Compiler parsing: Stacks are used in compilers to parse and evaluate code. The parser uses a stack to keep track of the current state of the parsing process.
- Undo/Redo functionality: Stacks are used in applications that allow users to undo or redo actions. Each action is pushed onto the stack, and when the user chooses to undo or redo an action, the corresponding action is popped off the stack.
- Browser history: Stacks are used in web browsers to keep track of the history of pages visited. Each page is pushed onto the stack when it is visited, and the back and forward buttons use the stack to navigate through the history.
- Tower of Hanoi problem: Stacks are used to solve the Tower of Hanoi problem, which involves moving a set of disks from one pole to another without placing a larger disk on top of a smaller one.
Advantages & Disadvantages of Stack on Array & Linked List
There are advantages and disadvantages to both the array and linked list implementations of a stack:
Array Implementation:
Advantages | Disadvantages |
Random Access: An array implementation of the Stack allows access to any random element from the Stack. | Fixed Size: The Stack implementation in an array is fixed in size. The array size decides how many numbers of the maximum elements in a Stack can be added. |
Efficient memory usage: The array implementation of a stack can be more efficient in terms of memory usage than a linked list implementation. | Stack overflow: If the maximum number of elements in the Stack is reached in an Array, then a Stack overflow error can occur. |
Linked List Implementation:
Advantages | Disadvantages |
Dynamic Size: The size of the Stack implementation in the Linked list is not limited by the array size. It means every time you can add an element to the top position, Linked List keeps growing according to the length of the Stack. | Sequential access: Since Linked List allows the addition of an element at any place, it does not provide access to the node randomly, which can make accessing a specific element in the Stack slower. |
Memory allocation: The moment a node is added to the Linked List, memory is allocated in the Linked List. Which is more efficient regarding memory usage than allocating a fixed-size array. | Extra memory usage: Linked lists require additional memory to store the pointers between nodes, which can result in slightly more memory usage than the array implementation. |
Conclusion
Learn about the stack data structure, properties, and common operations such as push and pop. Discover how stacks are used in algorithms and applications. Implement a stack in Python and understand its significance in computer science and problem-solving. Master the Last-In-First-Out (LIFO) principle and optimize your coding skills with stack-based approaches.