Question

need help with this confusing problem about java: Modify the quicksort to count the number of copies and comparisons it makes during a sort and then display the totals. the code would be in the poster.

Answer 1

class ArrayIns
{
private long[] theArray; // ref to array theArray
private int nElems; // number of data items
//--------------------------------------------------------------
public ArrayIns(int max) // constructor
{
theArray = new long[max]; // create the array
nElems = 0; // no items yet
}
//--------------------------------------------------------------
public void insert(long value) // put element into array
{
theArray[nElems] = value; // insert it
nElems++; // increment size
}
//--------------------------------------------------------------
public void display() // displays array contents
{
System.out.print("A=");
for(int j=0; j<nElems; j++) // for each element,
System.out.print(theArray[j] + " "); // display it
System.out.println("");
}
//--------------------------------------------------------------
public void quickSort()
{
recQuickSort(0, nElems-1);
}
//--------------------------------------------------------------
public void recQuickSort(int left, int right)
{
int size = right-left+1;
if(size <= 3) // manual sort if small
manualSort(left, right);
else // quicksort if large
{
long median = medianOf3(left, right);
int partition = partitionIt(left, right, median);
recQuickSort(left, partition-1);
recQuickSort(partition+1, right);
}
} // end recQuickSort()
//--------------------------------------------------------------
public long medianOf3(int left, int right)
{
int center = (left+right)/2;
// order left & center
if( theArray[left] > theArray[center] )
swap(left, center);
// order left & right
if( theArray[left] > theArray[right] )
swap(left, right);
// order center & right
if( theArray[center] > theArray[right] )
swap(center, right);

swap(center, right-1); // put pivot on right
return theArray[right-1]; // return median value
} // end medianOf3()
//--------------------------------------------------------------
public void swap(int dex1, int dex2) // swap two elements
{
long temp = theArray[dex1]; // A into temp
theArray[dex1] = theArray[dex2]; // B into A
theArray[dex2] = temp; // temp into B
} // end swap(
//--------------------------------------------------------------
public int partitionIt(int left, int right, long pivot)
{
int leftPtr = left; // right of first elem
int rightPtr = right - 1; // left of pivot

while(true)
{
while( theArray[++leftPtr] < pivot ) // find bigger
; // (nop)
while( theArray[--rightPtr] > pivot ) // find smaller
; // (nop)
if(leftPtr >= rightPtr) // if pointers cross,
break; // partition done
else // not crossed, so
swap(leftPtr, rightPtr); // swap elements
} // end while(true)
swap(leftPtr, right-1); // restore pivot
return leftPtr; // return pivot location
} // end partitionIt()
//--------------------------------------------------------------
public void manualSort(int left, int right)
{
int size = right-left+1;
if(size <= 1)
return; // no sort necessary
if(size == 2)
{ // 2-sort left and right
if( theArray[left] > theArray[right] )
swap(left, right);
return;
}
else // size is 3
{ // 3-sort left, center, & right
if( theArray[left] > theArray[right-1] )
swap(left, right-1); // left, center
if( theArray[left] > theArray[right] )
swap(left, right); // left, right
if( theArray[right-1] > theArray[right] )
swap(right-1, right); // center, right
}
} // end manualSort()
//--------------------------------------------------------------
} // end class ArrayIns
////////////////////////////////////////////////////////////////
class QuickSort2App
{
public static void main(String[] args)
{
int maxSize = 16; // array size
ArrayIns arr; // reference to array
arr = new ArrayIns(maxSize); // create the array

for(int j=0; j<maxSize; j++) // fill array with
{ // random numbers
long n = (int)(java.lang.Math.random()*99);
arr.insert(n);
}
arr.display(); // display items
arr.quickSort(); // quicksort them
arr.display(); // display them again
} // end main()
} // end class QuickSort2App
////////////////////////////////////////////////////////////////

Answer 2

A couple of object variables to count, getter methods to return the counts and increment them at each copy/comparison operation.

Answer 3

how i support ot do can u give example or can u explain more in detail

Answer 4

A couple of integer variables, initialized to zero, called say, copies and comparisons. A couple of methods, say getCopies() and getComparisons(). Increment them at appropriate places in your code.

Answer 5

k
thank