Quicksort
// C++ Implementation of the Quick Sort Algorithm.
#include <iostream>
using namespace std;
int partition(int arr[], int start, int end)
{
int pivot = arr[start];
int count = 0;
for (int i = start + 1; i <= end; i++) {
if (arr[i] <= pivot)
count++;
}
// Giving pivot element its correct position
int pivotIndex = start + count;
swap(arr[pivotIndex], arr[start]);
// Sorting left and right parts of the pivot element
int i = start, j = end;
while (i < pivotIndex && j > pivotIndex) {
while (arr[i] <= pivot) {
i++;
}
while (arr[j] > pivot) {
j--;
}
if (i < pivotIndex && j > pivotIndex) {
swap(arr[i++], arr[j--]);
}
}
return pivotIndex;
}
void quickSort(int arr[], int start, int end)
{
// base case
if (start >= end)
return;
// partitioning the array
int p = partition(arr, start, end);
// Sorting the left part
quickSort(arr, start, p - 1);
// Sorting the right part
quickSort(arr, p + 1, end);
}
int main()
{
int arr[] = { 9, 3, 4, 2, 1, 8 };
int n = 6;
quickSort(arr, 0, n - 1);
for (int i = 0; i < n; i++) {
cout << arr[i] << " ";
}
return 0;
}
MASOOM AGARWAL