Question

Java coding:

2. Write a method which takes a list list of int , and reverse it. // recursion

3.Write a method which takes a list list of strings , and reverse it. // in different way than the previous

3. Write a two methods which take a list and find the largest integer number in it.

Answer 1

2. Java_program for reversing the linked_list

class LinkedList {

   static Node head;

   static class Node {

       int data;
       Node next;

       Node(int d)
       {
           data = d;
           next = null;
       }
   }

   /* Function to reverse_linked_list */
   Node reverse(Node node)
   {
       Node prev = null;
       Node current = node;
       Node next = null;
       while (current != null) {
           next = current.next;
           current.next = prev;
           prev = current;
           current = next;
       }
       node = prev;
       return node;
   }

   // prints_content of double_linked_list
   void print List(Node node)
   {
       while (node != null) {
           System.out.print(node.data + " ");
           node = node.next;
       }
   }

   public static void main(String[] args)
   {
       LinkedList list = new LinkedList();
       list.head = new Node(65);
       list.head.next = new Node(25);
       list.head.next.next = new Node(14);
       list.head.next.next.next = new Node(20);

       System.out.println("Given Linked_list");
       list.printList(head);
       head = list.reverse(head);
       System.out.println("");
       System.out.println("Reversed linked_list ");
       list.printList(head);
   }
}

Output:
Given linked_list
65 25 14 20 
Reversed Linked_list 
20 14 25 65 

3. Take a list of strings , reverse it.

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;

class Main
{
public static void main(String[] args)
{
List<String> colors = new ArrayList<>(
Arrays.asList("GREEN", "YELLOW", "BLACK")); // INITIALIZE THE LIST

Collections.reverse(colors);
System.out.println(colors);
}
}

output: BLACK YELLOW GREEN

3. find the largest integer number from a list in java

Method_1: Iterative_Way

// Java Program to find largest integer number from a list
class Test
{
   static int arr[] = {100, 124, 145, 190, 808};
  
   // Method to find largest integer number from a list
   static int largest()
   {
       int i;
      
       // Initialize max integer
       int max = arr[0];
      
       // Traverse list (array) elements from second and
       // compare every element with current max
       for (i = 1; i < arr.length; i++)
           if (arr[i] > max)
               max = arr[i];
      
       return max;
   }
  
   // Driver_method
   public static void main(String[] args)
   {
       System.out.println("Largest in list is " + largest());
       }
}

Output:

Largest in list is 808

Method 2 : Sorting List

// Java Program to find largest integer number from a list
// arr[] of size n
import java .io.*;
import java.util.*;
  
class GFG
{     
   // returns maximum number from a list
   static int largest(int []arr,     
                   int n)
   {
       Arrays.sort(arr);
       return arr[n - 1];
   }
  
   // Driver code
   static public void main (String[] args)
   {
       int []arr = {10, 24, 45,
                   90, 980};
       int n = arr.length;
       System.out.println(largest(arr, n));
   }
}

Output: 980