JAVA EXAMPLE PROGRAMS

JAVA EXAMPLE PROGRAMS

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Program: Find Nth node from the end of Linked List


Problem Description:

Write a program to identify Nth node from the end of Linked List.

We have two approaches to identify Nth node from the end.

In First Approach:

  • First iterate through linked list and identify length.
  • Then again iterate (lenght-N) nodes from from head node.
  • The Node after the above iteration is the Nth node from the end.

In Second Approach:

  • We will define two temp Node references and they will be initially pointed to head node.
  • The two temp nodes are called as reference node & main node.
  • First iterate reference node to N nodes.
  • Then iterate both temp nodes one step at a time, till reference node is null.
  • Once after the above iteration, the main node represents the Nth node from the end node.



LlNthNodeFromLast
package com.java2novice.ds.linkedlist;

public class LlNthNodeFromLast {

    static class Node {
        int data;
        Node next;
        Node(int tmp) {data = tmp;}
    }

    static Node findNthNodeFromLastV1(Node head, int n) {

        /**
         * In this approach, first identify the length of the list.
         * Then do lenght-n iterations from head to reach nth node from last.
         */
        int length = 0;
        Node temp = head;
        while(temp != null) {
            temp = temp.next;
            length++;
        }
        System.out.println("length: "+length);
        for(int i=0;i<length-n;i++) {
            head = head.next;
        }
        return head;
    }

    static Node findNthNodeFromLastV2(Node head, int n) {

        /**
         * In this approach, we will use two pointers like refNode & mainNode
         * First we will traverse refNode by n times.
         * Then we will traverse both nodes one step at a time till refNode reaches null
         * The mainNode is the one we are looking for.
         */
        Node refNode = head;
        Node mainNode = head;
        if(head == null) {
            return null;
        }
        for(int i=0;i<n;i++) {
            if(refNode == null) {
                System.out.println("The n input size is more than linked list size");
                return null;
            }
            refNode = refNode.next;
        }

        while(refNode != null) {
            mainNode = mainNode.next;
            refNode = refNode.next;
        }

        return mainNode;
    }

    public static void main(String[] a) {

        Node n1 = new Node(23);
        Node n2 = new Node(29);
        Node n3 = new Node(69);
        Node n4 = new Node(85);
        Node n5 = new Node(40);
        Node n6 = new Node(45);
        Node n7 = new Node(54);
        n1.next = n2;
        n2.next = n3;
        n3.next = n4;
        n4.next = n5;
        n5.next = n6;
        n6.next = n7;

        Node nthNode = findNthNodeFromLastV2(n1, 3);
        System.out.println("Nth node value: "+nthNode.data);
    }
}

Output:
Nth node value: 40
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List Of All Interview Programs:

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  2. Identify middle element of a Linked List
  3. Identify given LinkedList is a palindrom or not using Stack.
  4. Remove duplicates from sorted linked list
  5. Find Nth node from the end of Linked List
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  7. Find length of a loop in a LinkedList.
  8. Detect and remove loop in a LinkedList.
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  16. Write a program to reverse a number.
  17. Write a program to convert decimal number to binary format.
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  22. Write a program to find top two maximum numbers in a array.
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  27. Write a program to find sum of each digit in the given number using recursion.
  28. Write a program to check the given number is a prime number or not?
  29. Write a program to find the given number is Armstrong number or not?
  30. Write a program to convert binary to decimal number.
  31. Write a program to check the given number is binary number or not?
  32. Write a program for Bubble Sort in java.
  33. Write a program for Insertion Sort in java.
  34. Write a program to implement hashcode and equals.
  35. How to get distinct elements from an array by avoiding duplicate elements?
  36. Write a program to get distinct word list from the given file.
  37. Write a program to get a line with max word count from the given file.
  38. Write a program to convert string to number without using Integer.parseInt() method.
  39. Write a program to find two lines with max characters in descending order.
  40. Write a program to find the sum of the first 1000 prime numbers.
  41. Find longest substring without repeating characters.
  42. Write a program to remove duplicates from sorted array.
  43. How to sort a Stack using a temporary Stack?
  44. Write a program to print all permutations of a given string.
  45. Implement Binary Search Tree (BST)
  46. Find min and max value from Binary Search Tree (BST)
  47. Find height of a Binary Search Tree (BST)
  48. Implement Binary Search Tree (BST) Level order traversal (breadth first).
  49. Implement Binary Search Tree (BST) pre-order traversal (depth first).
  50. Implement Binary Search Tree (BST) in-order traversal (depth first).
  51. Implement Binary Search Tree (BST) post-order traversal (depth first).
  52. How to check the given Binary Tree is Binary Search Tree (BST) or not?
  53. How to delete a node from Binary Search Tree (BST)?
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Knowledge Centre
What is wrapper class?
Everything in java is an object, except primitives. Primitives are int, short, long, boolean, etc. Since they are not objects, they cannot return as objects, and collection of objects. To support this, java provides wrapper classes to move primitives to objects. Some of the wrapper classes are Integer, Long, Boolean, etc.
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I'm Nataraja Gootooru, programmer by profession and passionate about technologies. All examples given here are as simple as possible to help beginners. The source code is compiled and tested in my dev environment.

If you come across any mistakes or bugs, please email me to [email protected].

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