QuickSort

QuickSort.cpp

// QkCTest.cpp : This file contains the 'main' function. Program execution begins and ends there.
//

//#include "pch.h"
#include <iostream>

using namespace std;

int myArray[] = { 21,10,5,2,21,19,6,9, 11, 17, 11, 8, 8, 8,12,0,0,0,0,19,21,21 };

const int glen = sizeof(myArray) / sizeof(int);

void Swap(int i, int j)
{
	int t = myArray[j];
	myArray[j] = myArray[i];
	myArray[i] = t;
	return;
}
void printArray()
{
	cout << "\nPrintArray - ";
	for (int i = 0; i < glen; ++i)
	{
		cout << myArray[i] << " ";
	}

	return;
}
void Partition(  int start, int end )
{
	int i = start + 1;
	int j = end;

	if (end <= start)
		return;

	cout << "\n\nPartition Enter : " << start << " := " << myArray[start] << ", " << j << ":= " << myArray[j];

	int pivot = myArray[start];

	cout << "\nPivot => " << start << ":= " << myArray[start];

	//printArray();


	if (start + 1 == j) // To Fix - why last two elements not exchanging using normal recursion; special case applied.
	{
		if (myArray[start] > myArray[j])
			Swap(start, j);
		
		return;
	}
		

	while (i < j) 
	{
		while (pivot >= myArray[i] && i < glen-1)
			++i;//move i forward till element is lesser then pivot

		while (pivot < myArray[j] && j > 0)
			--j; // move j backward till element is greater then pivot

		//cout << "\nSwaping :j = a[ " << j << " ]=" << myArray[j] << ",start = a[ " << start << "]= " << myArray[start];

		if (i < j)  // swap the elements 
		{
			Swap(i, j);
		}
		else
		{
			//cout << "\nPivot loc found " << j ;
			Swap(start, j);
		}

		
	}    //repeat
	
	printArray();

	Partition( start, j-1 );
	Partition( i, end);
	
}
void QuickSort( )
{
	Partition( 0, glen-1 );
	return;
}


int main()
{
    std::cout << "Hello Quick World!\n"; 

	
	QuickSort();
	std::cout << "Final Result - \n";
	printArray();
}