DataStructure/LinkedList.java at master · manumaini/DataStructure · GitHub

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public class LinkedList {

	public static Node head;

	static class Node{

		public int data;
		public Node next;

		public Node(int data ) {
			this.data = data;

		}


	}

	public static void addAtStart(Node node) {

		node.next = head;
		head = node;

		Node p = head;

		while(p != null) {

			System.out.print(p.data+" ");
			p = p.next;
		}
	}

	public static void addAtEnd(Node node) {

		Node p = head;

		while(p.next != null) {
			p = p.next;
		}

		p.next = node;

		p = head;

		while(p != null) {
			System.out.print(p.data+" ");
			p = p.next;
		}


	}

	public static void addAfter(int key , Node node) {

		if(head.data == key) {

			node.next = head.next;
			head.next = node;
			return;
		}

		Node p = head;

		while(p != null && p.data != key) {

			p = p.next;

		}

		node.next = p.next;
		p.next = node;


		p = head;
		while(p != null) {
			System.out.print(p.data+" ");
			p = p.next;
		}


		return;

	}


	public static void main(String args[]) {


		head = new Node(1);

		Node second = new Node(2);
		Node third = new Node(3);

		head.next = second;

		second.next = third;

		Node p = head;

		while(p != null) {

			System.out.print(p.data+" ");
			p = p.next;
		}


		// to add at the beginning
		System.out.print("\n");
		Node snode = new Node(0);
		addAtStart(snode);


		//to add at the end
		System.out.print("\n");
		Node enode =  new Node(4);
		addAtEnd(enode);


		//to add in the middle
		System.out.print("\n");
		Node mnode =  new Node(9);
		addAfter(3,mnode);


	}


}