quicksort

                                    #include<stdio.h>
int partition(int arr[], int low, int high) {
  int temp;
  int pivot = arr[high];
  int i = (low - 1); 
  for (int j = low; j <= high - 1; j++) {
    if (arr[j] <= pivot) { 
      i++; 
      temp = arr[i];
      arr[i] = arr[j];
      arr[j] = temp;
    } 
  } 
  temp = arr[i + 1];
  arr[i + 1] = arr[high];
  arr[high] = temp;
  return (i + 1); 
} 
void quick_sort(int arr[], int low, int high) { 
  if (low < high) {
    int pi = partition(arr, low, high); 
    quick_sort(arr, low, pi - 1); 
    quick_sort(arr, pi + 1, high); 
  } 
} 
int print(int arr[], int n) {
  for(int i = 0; i < n; i++) {
    printf("%d ", arr[i]);
  }
}

int main()
{
int n, i;
scanf("%d", &n);
int arr[n];
for(i = 0; i < n; i++)
{
scanf("%d", &arr[i]);
}
quick_sort(arr, 0, n - 1);
print(arr, n);
}

                                    algorithm quicksort(A, lo, hi) is
    if lo < hi then
        p := partition(A, lo, hi)
        quicksort(A, lo, p - 1)
        quicksort(A, p + 1, hi)

algorithm partition(A, lo, hi) is
    pivot := A[hi]
    i := lo
    for j := lo to hi do
        if A[j] < pivot then
            swap A[i] with A[j]
            i := i + 1
    swap A[i] with A[hi]
    return i

                                    /********** QuickSort(): sorts the vector 'list[]' **********/

/**** Compile QuickSort for strings ****/
#define QS_TYPE char*
#define QS_COMPARE(a,b) (strcmp((a),(b)))

/**** Compile QuickSort for integers ****/
//#define QS_TYPE int
//#define QS_COMPARE(a,b) ((a)-(b))

/**** Compile QuickSort for doubles, sort list in inverted order ****/
//#define QS_TYPE double
//#define QS_COMPARE(a,b) ((b)-(a))

void QuickSort(QS_TYPE list[], int beg, int end)
{
    QS_TYPE piv; QS_TYPE tmp;
    
    int  l,r,p;

    while (beg<end)    // This while loop will substitude the second recursive call
    {
        l = beg; p = (beg+end)/2; r = end;

        piv = list[p];

        while (1)
        {
            while ((l<=r) && (QS_COMPARE(list[l],piv) <= 0)) l++;
            while ((l<=r) && (QS_COMPARE(list[r],piv)  > 0)) r--;

            if (l>r) break;

            tmp=list[l]; list[l]=list[r]; list[r]=tmp;

            if (p==r) p=l;
            
            l++; r--;
        }

        list[p]=list[r]; list[r]=piv;
        r--;

        // Select the shorter side & call recursion. Modify input param. for loop
        if ((r-beg)<(end-l))   
        {
            QuickSort(list, beg, r);
            beg=l;
        }
        else
        {
            QuickSort(list, l, end);
            end=r;
        }
    }   
}

                                    //I Love Java
import java.io.*;
import java.util.*;
import java.util.stream.*;
import static java.util.Collections.*;

import static java.util.stream.Collectors.*;

public class Quick_Sort_P {

    static void swap(List<Integer> arr, int i, int j) {
        int temp = arr.get(i);
        arr.set(i, arr.get(j));
        arr.set(j, temp);
    }

    static int partition(List<Integer> arr, int low, int high) {

        int pivot = arr.get(high);
        int i = (low - 1);

        for (int j = low; j <= high - 1; j++) {

            if (arr.get(j) < pivot) {

                i++;
                swap(arr, i, j);
            }
        }
        swap(arr, i + 1, high);
        return (i + 1);
    }

    static void quickSort(List<Integer> arr, int low, int high) {
        if (low < high) {

            int pi = partition(arr, low, high);

            quickSort(arr, low, pi - 1);
            quickSort(arr, pi + 1, high);
        }
    }

    public static void main(String[] args) throws IOException {

        BufferedReader buffer = new BufferedReader(new InputStreamReader(System.in));

        List<Integer> arr = Stream.of(buffer.readLine().replaceAll("\\s+$", "").split(" ")).map(Integer::parseInt)
                .collect(toList());

        int n = arr.size();

        quickSort(arr, 0, n - 1);
        System.out.println("Sorted array: ");
        System.out.println(arr);
    }
}

                                    //last element selected as pivot
#include <iostream>

using namespace std;
void swap(int*,int*);
int partition(int arr[],int start,int end)
{
    int pivot=arr[end];
    int index=start;
    int i=start;
    while(i<end)
    {
        if(arr[i]<pivot)
        {
            swap(&arr[index],&arr[i]);
            index++;
        }
        i++;
    }
    swap(&arr[end],&arr[index]);
    return index;
}
void quicksort(int arr[],int start,int end)
{
    if(start<end)
    {
      int pindex=partition(arr,start,end);
      quicksort(arr,start,pindex-1);
      quicksort(arr,pindex+1,end);
    }
}
void display(int arr[],int n)
{
    for(int i=0;i<n;i++)
    {
        cout<<arr[i]<<" ";
    }
    cout<<endl;
}

int main()
{
    int n;
    cout<<"enter the size of the array:"<<endl;
    cin>>n;
    int arr[n];
    cout<<"enter the elements of the array:"<<endl;
    for(int i=0;i<n;i++)
    {
        cin>>arr[i];
    }
    cout<<"sorted array is:"<<endl;
    quicksort(arr,0,n-1);
    display(arr,n);

    return 0;
}
void swap(int *a,int*b)
{
    int temp=*a;
    *a=*b;
    *b=temp;
}