Question

In the most basic/easiest JAVA please change the following code into RECURISON make sure the program complies correctly. (It is currently in iterative.) please show comments how they are different after.

//public class

public class MergeSort

{

public static void mergeSort(int[] array)

{

int start;

int i;

int minScan;

int minValue;

int counter = 0;

/**

The outer loop iterates once for each element in the

array. The start variable marks the position where the scan should begin.

**/

for(start = 0; start < array.length-1; start++)

{

//assume the first element in the scannable area is the smallest value.

minScan = start;

minValue = array[start];

/**

Scan the array, starting at the 2nd element in

the scannable area. We are looking for the smallest value in

the scannable area.

**/

for(i = start+1;i < array.length;i++)

{

if(array[i] < minValue)

{

minValue = array[i];

minScan = i;

counter++;

}

}

//swap the element with the smallest value with the first element in the scannable area.

array[minScan] = array [start];

array[start] = minValue;

}

System.out.print("\nSwaps:" + counter); //displays swaps.

}

}

Answer 1

CODE:

public class MergeSort
{
//initialise counter variable to 0
static int counter=0;
  
public static void main(String args[] ) throws Exception {
  
//initialise new array
int[] intArray = new int[]{ 10,2,5,4,5,6,7,8,9,11 };
  
//call mergesort function
mergeSort(intArray, intArray.length, 0);
  
//displays swaps.
System.out.print("\nSwaps:" + counter);

}
  
  
static int minIndex(int a[], int i, int j)
{
//if starting ndex and size of the array are same
if (i == j)
return i;

// find minimum of remaining elements using recursion
int k = minIndex(a, i + 1, j);

// Return minimum of current and remaining.
return (a[i] < a[k])? i : k;
}

  
public static void mergeSort(int array[], int n, int position)
{

// Return when starting and size are same
if (position == n)
return;

// calling minimum index function for minimum index
int min = minIndex(array, position, n-1);

// Swapping when index nd minimum index are not same
if (min != position){
// swap
int temp = array[min];
array[min] = array[position];
array[position] = temp;
counter++;
}
// Recursively calling mergeSort function
mergeSort(array, n, position + 1);
}

}

OUTPUT: