Question

How would I add a quickSort function to the below C++ code to sort the randomly generated numbers?

#include <iostream>
#include <cstdlib>
#include <ctime>

using namespace std;
int i;
int array[10];
int odd;
int Max;
int counter = 0;

int main()

{
cout << "The 10 random elements are: ";
cout << endl;

srand ( time(0) );

for (int j = 0; j < 99; j++)
{
    i = rand() % 100;
    if (i != i - 1)
    array[j] = i;

else
{
    i = rand() % 100;
    array[j] = i;
}


}

for (int k = 0; k < 10 ; k++)
{
    cout << array[k] << "\n";

}

cout << endl;


return 0;
}

Answer 1

#include <iostream>
#include <cstdlib>
#include <ctime>
using namespace std;
int i;
int array[10];
int odd;
int Max;
int counter = 0;

int partition(int *a,int start,int end)
{
int pivot=a[end];
//P-index indicates the pivot value index

int P_index=start;
int i,t; //t is temporary variable

for(i=start;i<end;i++)
{
   if(a[i]<=pivot)
{
t=a[i];
a[i]=a[P_index];
a[P_index]=t;
P_index++;
}
}
//Now exchanging value of
//pivot and P-index
t=a[end];
a[end]=a[P_index];
a[P_index]=t;

//at last returning the pivot value index
return P_index;
}
//function driver for quicksort
void quicksort_fun(int *a,int start,int end)
{
if(start<end)
{
int P_index=partition(a,start,end);
//from start to index
quicksort_fun(a,start,P_index-1);
//index to end
quicksort_fun(a,P_index+1,end);
}
}

int main()

{
cout << "The 10 random elements are: ";
cout << endl;

srand ( time(0) );

for (int j = 0; j < 99; j++)
{
i = rand() % 100;
if (i != i - 1)
array[j] = i;

else
{
i = rand() % 100;
array[j] = i;
}

}
cout<<"Before sorting : ";
for (int k = 0; k < 10 ; k++)
{
cout << array[k] << " ";

}
quicksort_fun(array,0,9);
cout<<"\nAfter sorting using quicksort: ";
for (int k = 0; k < 10 ; k++)
{
cout << array[k] << " ";

}
cout << endl;

return 0;
}