In the context of stacks and queues, what are the main differences between the terms "FILO" and "LIFO"? How do these concepts affect the order in which items are added and removed from each data structure?
TUTORIAL
Tutorial: Stacks
A stack is a linear data
Stack Operations:
1) Push: Add an element to the top of the stack. 2) Pop: Remove the top element from the stack. 3) Peek: Inspect the value of the top element without removing it. 4) IsEmpty: Check if the stack is empty.
Stack Visualization:
1) Start with an empty stack:
Top -> NULL
2) Push elements onto the stack: Push 10:
Top -> Node(10, NULL)
Push 20:
Top -> Node(20, Node(10, NULL))
Push 30
Top -> Node(30, Node(20, Node(10, NULL)))
3) Peek the top element:
Peek:
Top -> Node(30, Node(20, Node(10, NULL)))
Output: 30
4) Pop the top element:
Pop
Top -> Node(20, Node(10, NULL))
Popped: 30
5) Check if the stack is empty:
IsEmpty:
Top -> Node(20, Node(10, NULL))
Output: Stack is not empty
6) Pop remaining elements:
Pop:
Top -> Node(10, NULL)
Popped: 20
Pop:
Top -> NULL
Popped: 10
7)Check if the stack is empty:
IsEmpty:
Top -> NULL
Output: Stack is empty
Let’s implement the stack using a linked list in Java:
class Node {
int value;
Node next;
Node(int value) {
this.value = value;
this.next = null;
}
}
class Stack {
Node top;
Stack() {
this.top = null;
}
void push(int value) {
Node newNode = new Node(value);
newNode.next = top;
top = newNode;
}
int pop() {
if (isEmpty()) {
throw new RuntimeException("Stack is empty");
}
int poppedValue = top.value;
top = top.next;
return poppedValue;
}
int peek() {
if (isEmpty()) {
throw new RuntimeException("Stack is empty");
}
return top.value;
}
boolean isEmpty() {
return top == null;
}
}
Tutorial: Queues
A queue is a linear data structure that follows the First In First Out (FIFO) principle, meaning that the first element added to the queue will be the first one to be removed. Queues are commonly used in scenarios like task scheduling, printer job management, and breadth-first search algorithms.
Queue Operations:
1) Enqueue: Add an element to the rear of the queue. 2) Dequeue: Remove the front element from the queue. 3) Peek: Inspect the value of the front element without removing it. 4) IsEmpty: Check if the queue is empty.
Queue Visualization: Let’s create a queue and perform various operations step by step:
1) Start with an empty queue:
Front -> NULL
Rear -> NULL
2)Enqueue elements onto the queue:
Enqueue 10:
Front -> Node(10, NULL)
Rear -> Node(10, NULL)
Enqueue 20:
Front -> Node(10, Node(20, NULL))
Rear -> Node(20, NULL)
Enqueue 30:
Front -> Node(10, Node(20, Node(30, NULL)))
Rear -> Node(30, NULL)
3) Peek the front element:
Peek:
Front -> Node(10, Node(20, Node(30, NULL)))
Output: 10
4) Dequeue the front element:
Dequeue:
Front -> Node(20, Node(30, NULL))
Dequeued: 10
5) Check if the queue is empty:
IsEmpty:
Front -> Node(20, Node(30, NULL))
Output: Queue is not empty
6) Dequeue remaining elements:
Dequeue:
Front -> Node(30, NULL)
Dequeued: 20
Dequeue:
Front -> NULL
Dequeued: 30
7) Check if the queue is empty:
IsEmpty:
Front -> NULL
Output: Queue is empty
Let’s implement the queue using a linked list in Java:
class Node {
int value;
Node next;
Node(int value) {
this.value = value;
this.next = null;
}
}
class Queue {
Node front;
Node rear;
Queue() {
this.front = null;
this.rear = null;
}
void enqueue(int value) {
Node newNode = new Node(value);
if (isEmpty()) {
front = newNode;
} else {
rear.next = newNode;
}
rear = newNode;
}
int dequeue() {
if (isEmpty()) {
throw new RuntimeException("Queue is empty");
}
int dequeuedValue = front.value;
front = front.next;
if (front == null) {
rear = null;
}
return dequeuedValue;
}
int peek() {
if (isEmpty()) {
throw new RuntimeException("Queue is empty");
}
return front.value;
}
boolean isEmpty() {
return front == null;
}
}
Conclusion: Stacks and queues are essential data structures that can be used to solve various programming problems efficiently. Understanding their principles, operations, and implementations in Java will greatly enhance your ability to design robust algorithms and handle real-world scenarios. Mastering stacks and queues will lay a solid foundation for dealing with more complex data structures and algorithms in your Java programming journey.