quicksearch.cpp

#include <bits/stdc++.h> 

using namespace std;  

  

// A utility function to swap two elements  

void swap(int* a, int* b)  

{  

    int t = *a;  

    *a = *b;  

    *b = t;  

}  

  

/* This function takes last element as pivot, places  

the pivot element at its correct position in sorted  

array, and places all smaller (smaller than pivot)  

to left of pivot and all greater elements to right  

of pivot */

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 current element is smaller than the pivot  

        if (arr[j] < pivot)  

        {  

            i++; // increment index of smaller element  

            swap(&arr[i], &arr[j]);  

        }  

    }  

    swap(&arr[i + 1], &arr[high]);  

    return (i + 1);  

}  

  

/* The main function that implements QuickSort  

arr[] --> Array to be sorted,  

low --> Starting index,  

high --> Ending index */

void quickSort(int arr[], int low, int high)  

{  

    if (low < high)  

    {  

        /* pi is partitioning index, arr[p] is now  

        at right place */

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

  

        // Separately sort elements before  

        // partition and after partition  

        quickSort(arr, low, pi - 1);  

        quickSort(arr, pi + 1, high);  

    }  

}  

  

/* Function to print an array */

void printArray(int arr[], int size)  

{  

    int i;  

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

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

    cout << endl;  

}  

  

// Driver Code 

int main()  

{  

    int arr[] = {10, 7, 8, 9, 1, 5};  

    int n = sizeof(arr) / sizeof(arr[0]);  

    quickSort(arr, 0, n - 1);  

    cout << "Sorted array: \n";  

    printArray(arr, n);  

    return 0;  

}