Skip to main content

Left Rotation in an Array using Java

Left Rotation in an Array using Java

There are two methods implemented by me here :-

1) Using extra Array 
  1.  Get new position of  a current element using formula.
  2.  Add the element in the new position in a new array.


2) Using same Array:- This is little bit complex

  1. hold variable at index i.
  2. find new index for variable.
  3. hold variable present at new index.
  4. place variable at index i to this new index.
  5. assign i to new index variable.
  6. repeat steps until count is not equal to lenght of an array which simply means all variable got covered.



package Arrays;

/*
 * 12345 to 34512
 */

/*
 * sample input
 * 5 4(d=4 that is 4 rotations)
 1 2 3 4 5
 sample output
 51234
 */
public class LeftRotation {
 
 public static void printArray(int[] arr)
 {
  
  for(int i=0;i<arr.length;i++)
  {
  System.out.print(" "+arr[i]);
  }
  System.out.println(" ");
 }
 
 //method which returns rotated array using extra array
 public static int[] leftRotate(int[] arr, int rotation)
 {
  int temparr[]=new int[arr.length];
  int pos;
  for(int i=0;i<arr.length;i++)
  {
   pos=(arr.length+(i-rotation))%arr.length;
   temparr[pos]=arr[i];
  }
  printArray(temparr);
  
  return temparr;
 }

 //method which returns rotated array using same array
 public static int[] leftRotate2(int[] arr, int rotation)
 {
  
  int pos,tempinit,temppos=arr[0],i=0,c=0;
  
  while(c!=arr.length){
   tempinit=temppos;
   pos=(arr.length+(i-rotation))%arr.length;
   temppos=arr[pos];
   arr[pos]=tempinit; 
   i=pos;
   c++;
  }
  
  printArray(arr);
  
  return arr;
 }

 
 
 public static void main(String[] args)
 {
  int[] arr={1,2,3,4,5};
  leftRotate(arr, 3);
  leftRotate2(arr, 3);
 }
}

Comments

.

Popular posts from this blog

Career in software engineering : Roles to know

when someone starts a career in software engineering there are plenty of options. Although most graduates have the same degree, everyone starts in a different role. Developer / Coder - Engineers in this role get a chance to actually implement and write software. At the start of a career mostly it is about fixing defects in existing software then taking small changes to the software and eventually getting to the point to handle and implement more complex changes.  Quality analysts / Quality engineers - Engineers in this role test and automate software. This is a challenging role where one has to know about the full functionality of the software and test accurately so the software built is of high quality. This role also involves the automation of test cases and preparing a test suite that can be run and detect issues automatically. Release Engineers - Once the software is built and tested release engineers are responsible for pushing a set of code to production. A production is a plac

5 books that your college doesn’t tell to read seriously for PLACEMENTS

1.               Let us C - It can be the best book to pick in your first semester itself. The book is written in a very simple style so you can easily grasp most of the concepts of programming by just working hard on it. It will help you in building basics of programming around c language. 2.               HEAD FIRST JAVA- This book you should buy in third semester and invest your whole second year into it by working on all the codes. This book will help you teaching the concepts in a very attractive way. You will never bore while working  through this book. 3.               Data Structure Made Easy In Java - As soon you finished studying core java in the 4 th semester just pick this book to understand the logic’s of data structure and algorithms. It will help you to go deep inside this subject from which questions are frequently asked in all the interviews. This book carries a great set of problems that will help in developing intellectual knowledge around