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 ...

TWO SUM -LEET CODE PROBLEM 1

   https://leetcode.com/problems/two-sum/ Given an array of integers  nums  and an integer  target , return  indices of the two numbers such that they add up to  target . You may assume that each input would have  exactly  one solution , and you may not use the  same  element twice. You can return the answer in any order.   Example 1: Input: nums = [2,7,11,15], target = 9 Output: [0,1] Output: Because nums[0] + nums[1] == 9, we return [0, 1]. Example 2: Input: nums = [3,2,4], target = 6 Output: [1,2] Example 3: Input: nums = [3,3], target = 6 Output: [0,1] class Solution {     public int[] twoSum(int[] nums, int target) {              HashMap<Integer,Integer> map=new HashMap<Integer,Integer>();                  for(int i=0;i<nums.length;i++){                      ...