Write a function rotate(ar[], d, n) that rotates arr[] of size n by d elements. * @author paveynganpi

ProgramForArrayRotation .java

/**
 * 
 * Write a function rotate(ar[], d, n) that rotates arr[] of size n by d elements.
 * @author paveynganpi
 *
 */
 
 //reversal solution
 /**
 * 
 * Write a function rotate(ar[], d, n) that rotates arr[] of size n by d elements.
 * @author paveynganpi
 *
 */
public class ProgramForArrayRotation {
	
	public static void leftRotate(int[] arr, int d, int n){
		
		reverse(arr,0,d-1);
		reverse(arr,d,n-1);
		reverse(arr,0,n-1);
		
	}
	
	public static void printArr(int[] arr){
		for(int i=0;i<arr.length;i++){
			System.out.print( arr[i] + " ");
		}
		System.out.println();
		
	}
	
	public static void reverse(int[] arr,int start, int end){
		
		int i;
		  int temp;
		  while(start < end)
		  {
		    temp = arr[start];
		    arr[start] = arr[end];
		    arr[end] = temp;
		    start++;
		    end--;
		  }
		
	}
	public static void main(String[]main){
			
		int[] arr = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12};
		printArr(arr);
		System.out.println();
		leftRotate(arr,3,arr.length);
		printArr(arr);
		
	}

}

 
 
 
 //gcd solution
public class ProgramForArrayRotation {
	
	public static void leftRotate(int[] arr, int d, int n){
		
		int i;
		int j;
		int k;
		int temp;
		
		for(i=0; i<gcd(d,n); i++){
			
			j=i;
		    temp = arr[i]; 
		    while(true){
		    	k = j+d;
		    	if(k>=n){
		    		k=k-n;
		    	}
		    	if(k==i){
		    		break;
		    	}
		    	arr[j] = arr[k];
		    	j=k;
		    	
		    }
		    arr[j] = temp;
		    
		}
	}
	
	public static void printArr(int[] arr){
		for(int i=0;i<arr.length;i++){
			System.out.print( arr[i] + " ");
		}
		
	}
	
	public static int gcd(int a , int b){
		
		if(b==0){return a;}
		else{
			return gcd(b,a%b);
		}
	}
	public static void main(String[]main){
			
		int[] arr = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12};
		printArr(arr);
		System.out.println();
		leftRotate(arr,3,arr.length);
		printArr(arr);
		
	}

}