QuickSort | C ++ implementation of QuickSort ; A utility function to swap two elements ; 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 ; pivot ; Index of smaller element and indicates the right position of pivot found so far ; If current element is smaller than the pivot ; i ++ ; increment index of smaller element ; The main function that implements QuickSort arr [ ] -- > Array to be sorted , low -- > Starting index , high -- > Ending index ; pi is partitioning index , arr [ p ] is now at right place ; Separately sort elements before partition and after partition ; Function to print an array ; Driver Code
#include <bits/stdc++.h> NEW_LINE using namespace std ; 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 ] ; int i = ( low - 1 ) ; for ( int j = low ; j <= high - 1 ; j ++ ) { if ( arr [ j ] < pivot ) { 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 ++ ) cout << arr [ i ] << " ▁ " ; cout << endl ; } 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 : ▁ STRNEWLINE " ; printArray ( arr , n ) ; return 0 ; }