C Program for Block Swapping Algorithm

February 23, 2022

Program for Block Swapping Algorithm in C

Today we will learn about how to make  C Program for Block Swapping Algorithm  programming language.On rotation, we will shift the one element to the last position and shift the next elements to one position. 

Block Swapping Algorithm
While loop in C

Method Discussed

  • Method 1 : Recursive Way
  • Method 2 : Iterative Way

Method 1 :

  • Declare two arrays A and B,
  • Copy all the elements from index 0 to (d-1) to A[] and from index d to n-1 to B[].
  • Run a loop till size of array A is equal to size of B[].
  • If A is longer, divide A into Al and Ar such that Al is of same length as B Swap Al and B to change AlArB into BArAl.
  • Now B is at its final place, so recur on pieces of A. 
  • Finally when A and B are of equal size, block swap them.

Method 1 : Code in C

#include<stdio.h>
 
void printArray(int arr[], int size);
void swap(int arr[], int fi, int si, int d);
 
void leftRotate(int arr[], int d, int n)
{
    if(d == 0 || d == n)
        return;
     
    if(n-d == d){
        swap(arr, 0, n-d, d);  
        return;
    } 
     
    if(d < n-d){ 
        swap(arr, 0, n-d, d);
        leftRotate(arr, d, n-d);   
    }   
    else{
        swap(arr, 0, d, n-d);
        leftRotate(arr+n-d, 2*d-n, d);
    }
}
 

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 program to test above functions */
int main()
{
   int arr[] = {10, 20, 30, 40, 50, 60, 70};
   leftRotate(arr, 2, 7);
   
   for(int i = 0; i < 7; i++)
    printf("%d ", arr[i]);
   
   return 0;
}

Output

30 40 50 60 70 10 20

Method 2 :

In this method we implement the iterative approach for the algorithm discussed in method 1.

Method 2 : Code in C

#include<stdio.h>

void swap(int arr[], int fi, int si, int d);
 
void leftRotate(int arr[], int d, int n)
{
    int i, j;
    if(d == 0 || d == n)
        return;
  
    if(d > n)
        d = d % n;
    
    i = d;
    j = n - d;
    
    while (i != j){
        if(i < j) {
            swap(arr, d-i, d+j-i, i);
            j -= i;
        }
        else {
            swap(arr, d-i, d, j);
            i -= j;
        }
    }
  
    swap(arr, d-i, d, i);
}
 

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 program to test above functions */
int main()
{
   int arr[] = {10, 20, 30, 40, 50, 60, 70};
   leftRotate(arr, 2, 7);
   
   for(int i = 0; i < 7; i++)
    printf("%d ", arr[i]);
   
   return 0;
}

Output

30 40 50 60 70 10 20