Quick Sort in C++

 A simple program quick sort in C++ program that I wrote while I am learning C++ programming.

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Program Listing

// quick_sort.cpp

// Prof. Jake R. Pomperada, MAED-IT, MIT

// www.jakerpomperada.com / www.jakerpomperada.blogspot.com

// jakerpomperada@gmail.com

// Bacolod City, Negros Occidental Philippines

#include <iostream>

#include <cstdlib>

 

using namespace std;

void swap_numbers(int *a, int *b)

{

int temp; 

temp = *a;

*a = *b;

*b = temp;

}

 

int Partition(int a[], int low, int high)

{

int pivot, index, i;

index = low;

pivot = high;

 

for(i=low; i < high; i++)

{

if(a[i] < a[pivot])

{

swap_numbers(&a[i], &a[index]);

index++;

}

}

swap_numbers(&a[pivot], &a[index]);

 

return index;

}

 

int RandomPivotPartition(int a[], int low, int high)

{

int pvt, n, temp;

n = rand();

pvt = low + n%(high-low+1);

 

swap_numbers(&a[high], &a[pvt]);

 

return Partition(a, low, high);

}

 

int QuickSort(int a[], int low, int high)

{

int pindex;

if(low < high)

{

pindex = RandomPivotPartition(a, low, high);

QuickSort(a, low, pindex-1);

QuickSort(a, pindex+1, high);

}

return 0;

}

 

int main()

{

int n=0, i=0;

cout <<"\n";

cout <<"\t\tQuick Sort in C++";

cout <<"\n\n";

cout<<"\tHow many items to be sorted? ";

cin>>n;

 

int arr[n];

for(i = 0; i < n; i++)

{

cout<<"\tEnter item no. "<<i+1<<": ";

cin>>arr[i];

}

    cout <<"\n";

  cout<<"\tUnSorted Items\n ";

cout <<"\n";

cout <<"\t";

for (i =0; i < n; i++) {

cout<<" ,"<<arr[i];

}

    cout <<"\n";

QuickSort(arr, 0, n-1);

    cout <<"\n\n";

cout<<"\tSorted Item \n";

cout <<"\n";

cout <<"\t";

for (i = 0; i < n; i++) {

cout<<" ,"<<arr[i];

}

    cout <<"\n\n";

cout <<"\tEnd of Program";   

cout <<"\n";

}