Question

The goal is to generate some random number and output a sorted list by quicksort. what do I need to add in my main to accomplish that? i also want it to output the run time. thank you

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

using namespace std;
/* C implementation QuickSort */
#include<stdio.h>
void swap(int* a, int* b)
{
   int t = *a;
   *a = *b;
   *b = t;
}
int partition(int arr[], int low, int high)
{
   int pivot = arr[high]; // pivot
   int i = (low - 1); // Index of smaller element

   for (int j = low; j <= high - 1; j++)
   {
  
       if (arr[j] <= pivot)
       {
           i++;   
           swap(&arr[i], &arr[j]);
       }
   }
   swap(&arr[i + 1], &arr[high]);
   return (i + 1);
}

void quickSort(int arr[], int low, int high)
{
   if (low < high)
   {
      
       int pi = partition(arr, low, high);

       quickSort(arr, low, pi - 1);
       quickSort(arr, pi + 1, high);
   }
}
void printArray(int arr[], int size)
{
   int i;
   for (i = 0; i < size; i++)
       printf("%d ", arr[i]);
   printf("n");
}
int main()
{
   const unsigned int Arraysize =6;
   int numbArray[Arraysize];
  
   for (int i = 0; i < Arraysize; i++)
   {
       numbArray[i] = rand() % 1000;
       cout << numbArray[i] << endl;
   }
   return 0;
}

Answer 1

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

using namespace std;
/* C implementation QuickSort */
#include<stdio.h>
void swap(int* a, int* b)
{
int t = *a;
*a = *b;
*b = t;
}
int partition(int arr[], int low, int high)
{
int pivot = arr[high]; // pivot
int i = (low - 1); // Index of smaller element

for (int j = low; j <= high - 1; j++)
{
  
if (arr[j] <= pivot)
{
i++;   
swap(&arr[i], &arr[j]);
}
}
swap(&arr[i + 1], &arr[high]);
return (i + 1);
}

void quickSort(int arr[], int low, int high)
{
if (low < high)
{
  
int pi = partition(arr, low, high);

quickSort(arr, low, pi - 1);
quickSort(arr, pi + 1, high);
}
}
void printArray(int arr[], int size)
{
int i;
for (i = 0; i < size; i++)
printf("%d ", arr[i]);
printf("\n");
}
int main()
{
const unsigned int Arraysize =6;
int numbArray[Arraysize];
  
for (int i = 0; i < Arraysize; i++)
{
numbArray[i] = rand() % 1000;
//cout << numbArray[i] << endl;
}
//display the array elements before sorting
cout<<endl<<"Before sorting the array is : ";
//call to printArray()
printArray(numbArray,Arraysize);
//call to quicksort()
quickSort(numbArray,0,Arraysize-1);
cout<<endl<<"Sorted Array is : ";
//call to printArray()
printArray(numbArray,Arraysize);
return 0;
}

OUTPUT

iN BEST CASE IT WILL TAKE O(nlogn) and in worst case it will take O(n²)