Java Program for Block swap algorithm for array rotation

import java.util.*;

class GFG 
{
    // Wrapper over the recursive function leftRotateRec()
    // It left rotates arr[] by d.
    public static void leftRotate(int arr[], int d, 
                                                int n)
    {
        leftRotateRec(arr, 0, d, n);
    }

    public static void leftRotateRec(int arr[], int i, 
                                  int d, int n)
    {
        /* Return If number of elements to be rotated 
        is zero or equal to array size */
        if(d == 0 || d == n) 
            return; 
        
        /*If number of elements to be rotated 
        is exactly half of array size */
        if(n - d == d) 
        { 
            swap(arr, i, n - d + i, d); 
            return; 
        } 
        
        /* If A is shorter*/    
        if(d < n - d) 
        { 
            swap(arr, i, n - d + i, d); 
            leftRotateRec(arr, i, d, n - d);     
        } 
        else /* If B is shorter*/    
        { 
            swap(arr, i, d, n - d); 
            leftRotateRec(arr, n - d + i, 2 * d - n, d); /*This is tricky*/
        } 
    }

/*UTILITY FUNCTIONS*/
/* function to print an array */
public static void printArray(int arr[], int size) 
{ 
    int i; 
    for(i = 0; i < size; i++) 
        System.out.print(arr[i] + " "); 
    System.out.println(); 
} 

/*This function swaps d elements 
starting at index fi with d elements
starting at index si */
public static void swap(int arr[], int fi,
                        int si, int d) 
{ 
    int i, temp; 
    for(i = 0; i < d; i++) 
    { 
        temp = arr[fi + i]; 
        arr[fi + i] = arr[si + i]; 
        arr[si + i] = temp; 
    } 
} 

// Driver Code
public static void main (String[] args) 
{
    int arr[] = {1, 2, 3, 4, 5, 6, 7}; 
    leftRotate(arr, 2, 7); 
    printArray(arr, 7);     
}
}

// This code is contributed by codeseeker

//Java code for above implementation
static void leftRotate(int arr[], int d, int n) 
{ 
int i, j; 
if(d == 0 || d == n) 
    return; 
i = d; 
j = n - d; 
while (i != j) 
{ 
    if(i < j) /*A is shorter*/
    { 
    swap(arr, d-i, d+j-i, i); 
    j -= i; 
    } 
    else /*B is shorter*/
    { 
    swap(arr, d-i, d, j); 
    i -= j; 
    } 
    // printArray(arr, 7); 
} 
/*Finally, block swap A and B*/
swap(arr, d-i, d, i); 
}