Updated StackOfLinkedList.java

I made the code shorter and less prone to mistakes by removing the "size" variable altogether from the LinkedList class. I found that after each push/pop operation, changing the value of size did make the code more efficient, but made it more prone to mistakes. So, for empty stack, a simple "head == null" was enough, which has been incorporated.
This commit is contained in:
Ojas Saxena
2019-03-04 15:05:15 +05:30
committed by GitHub
parent dda712c0c7
commit d60f836861

View File

@ -25,9 +25,7 @@ class StackOfLinkedList {
stack.pop(); stack.pop();
System.out.println("Top element of stack currently is: " + stack.peek()); System.out.println("Top element of stack currently is: " + stack.peek());
} }
} }
// A node class // A node class
@ -51,11 +49,10 @@ class Node {
class LinkedListStack { class LinkedListStack {
Node head = null; Node head = null;
int size = 0;
public void push(int x) { public void push(int x) {
Node n = new Node(x); Node n = new Node(x);
if (getSize() == 0) { if (head == null) {
head = n; head = n;
} }
else { else {
@ -63,47 +60,55 @@ class LinkedListStack {
n.next = temp; n.next = temp;
head = n; head = n;
} }
size++;
} }
public void pop() { public void pop() {
if (getSize() == 0) { if (head == null) {
System.out.println("Empty stack. Nothing to pop"); System.out.println("Empty stack. Nothing to pop");
} }
Node temp = head; Node temp = head;
head = head.next; head = head.next;
size--;
System.out.println("Popped element is: " + temp.data); System.out.println("Popped element is: " + temp.data);
} }
public int peek() { public int peek() {
if (getSize() == 0) { if (head == null) {
return -1; return -1;
} }
return head.data; return head.data;
} }
public void printStack() { public void printStack() {
Node temp = head; Node temp = head;
System.out.println("Stack is printed as below: "); System.out.println("Stack is printed as below: ");
while (temp != null) { while (temp != null) {
System.out.println(temp.data + " "); if(temp.next == null) {
System.out.print(temp.data);
}
else {
System.out.print(temp.data + " -> ");
}
temp = temp.next; temp = temp.next;
} }
System.out.println(); System.out.println();
} }
public boolean isEmpty() { public boolean isEmpty() {
return getSize() == 0; return head == null;
} }
public int getSize() { public int getSize() {
if(head == null)
return 0;
else {
int size = 1;
Node temp = head;
while(temp.next != null) {
temp = temp.next;
size++;
}
return size; return size;
} }
}
} }