circular left shift of an array by n positions in java

Question

I am trying to do the circular left shift of an array by n positions using only a single 1D array. I can do it in two arrays, but I haven\'t figured out how to do it using o

Answer 1

Another alternative would be to wrap up your own structure, which includes the array and the index of virtual zero.

Answer 2

Maybe an old post.. but here you are my solution (where A obviously is the array and K the number of positions).

public int[] solution(int[] A, int K){
    int[] result = new int[A.length];

    for (int i = 0; i<A.length; i++){
        result[(i+K)%A.length] = A[i];
    }
    return result;
}

Answer 3

How about this?

    // Left shift the array in O(n) with O(1) space.

public static void leftShift(int[] array, int n) {
    int temp;
    int len = array.length;
    for (int i = 0; i < n; i++) {
        temp = array[len - n + i];
        array[len - n + i] = array[i];
        array[i] = array[n + i];
        array[n + i] = temp;
    }
}

Answer 4

Java 8 version:

public class Sample {
   public static void main(String[] args) {
     int[] answer = solution(new int[] {1,2,3,4}, 2);
     Arrays.stream(answer).forEach(System.out::print);
   }

   public static int[] solution(int[] A, int K) {
     List<Integer> numbers = 
     IntStream.of(A).boxed().collect(Collectors.toList());
     Collections.rotate(numbers, K);
     return numbers.stream().mapToInt(n -> n).toArray();
  }
}

Answer 5

Checkout this github link:

https://github.com/techpanja/interviewproblems/blob/master/src/arrays/circularshiftintarray/CircularShiftArray.java

circularShiftToLeftInPlace

Answer 6

Below I have implemented a sample solution to left shift or right shift the array by n element.

class RotateArrayByN {

    public void leftRotate(int arr[], int d, int n)
    {
        for (int i = 0; i < d; i++)
            leftRotatebyOne(arr, n);
    }

    public void rightRotate(int[] arr,int d, int n){
        for(int i=0;i<d;i++)
            rightRotatebyOne(arr,n);
    }

    public void leftRotatebyOne(int arr[], int n)
    {
        int i, temp;
        temp = arr[0];
        for (i = 0; i < n - 1; i++)
            arr[i] = arr[i + 1];
        arr[i] = temp;
    }

    public void rightRotatebyOne(int[] arr,int n){

        int temp=arr[n-1];
        for (int i=n-1;i>0;i--) {
            arr[i] = arr[i - 1];
        }
        arr[0]=temp;

    }

  public void printArray(int arr[], int n)
    {
        for (int i = 0; i < n; i++)
            System.out.print(arr[i] + " ");

        System.out.println();
    }


    public static void main(String[] args)
    {
        RotateArrayByN rotate = new RotateArrayByN();
        int arr[] = { 1, 2, 3, 4, 5, 6, 7 };
        System.out.println("Left Rotate");
        rotate.leftRotate(arr, 2, 7);
        rotate.printArray(arr, 7);

       //System.out.println("Right Rotate");
        //rotate.rightRotate(arr,2,7);
       // rotate.printArray(arr,7);
    }
} 

I have commented out the right shift.