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Operations on Stack
Introduction to Stack Operations:
A stack is a linear data structure that follows the Last In First Out (LIFO) principle. The main operations of a stack are Push, Pop, Peek, and isEmpty. These operations allow us to add, remove, and inspect elements in the stack.
Push Operation
Concept:
The push operation adds an element to the top of the stack. If the stack is full, it is said to be in an overflow state.
// Diagram:
// Initial Stack: [ ]
// After push(10): [10]
// After push(20): [10, 20]
Stack stack = new Stack<>();
stack.push(10);
stack.push(20);
System.out.println(stack); // Output: [10, 20]
Pop Operation
Concept:
The pop operation removes the element at the top of the stack. If the stack is empty, it is said to be in an underflow state.
// Diagram:
// Initial Stack: [10, 20]
// After pop(): [10]
// Popped Element: 20
Stack stack = new Stack<>();
stack.push(10);
stack.push(20);
int poppedElement = stack.pop();
System.out.println(stack); // Output: [10]
System.out.println("Popped Element: " + poppedElement); // Output: 20
Peek Operation
Concept:
The peek operation returns the element at the top of the stack without removing it.
// Diagram:
// Stack: [10, 20]
// Top Element: 20
Stack stack = new Stack<>();
stack.push(10);
stack.push(20);
int topElement = stack.peek();
System.out.println("Top Element: " + topElement); // Output: 20
isEmpty Operation
Concept:
The isEmpty operation checks whether the stack is empty or not. It returns true if the stack is empty, otherwise false.
// Diagram:
// Stack: [10, 20]
// isEmpty: false
Stack stack = new Stack<>();
stack.push(10);
stack.push(20);
boolean isEmpty = stack.isEmpty();
System.out.println("Is Stack Empty? " + isEmpty); // Output: false
Search Operation
Concept:
The search operation returns the 1-based position of the element from the top of the stack. If the element is not found, it returns -1.
// Diagram:
// Stack: [10, 20, 30]
// Position of 20: 2
Stack stack = new Stack<>();
stack.push(10);
stack.push(20);
stack.push(30);
int position = stack.search(20);
System.out.println("Position of 20: " + position); // Output: 2
