Quicksort的算法分析及C++实现

//
//  main.cpp
//  quicksort
//
//  Created by lingnan on 10/21/15.
//  Copyright (c) 2015 lingnan. All rights reserved.
//

#include <iostream>
using namespace std;

int partition(int arr[], int left, int right){
    int pivot = arr[right];                 //choose the rightest element as the pivot
    int curr = left;
    for(int i=left; i<right; i++){
        if(pivot > arr[i]){                 //always put smaller element in the left
            swap(arr[curr], arr[i]);
            curr++;
        }
    }
    swap(arr[curr], arr[right]);           //at last, put pivot element in the position it should be
    return curr;
}

void quicksort(int arr[], int left, int right){
    if(left < right){
        int p = partition(arr, left, right);
        quicksort(arr, left, p-1);
        quicksort(arr, p+1, right);
    }
}

void printArray(int arr[], int n){
      cout <<"The final result after quicksort is:" <<endl;
    for(int i=0; i<n; i++){
      cout <<arr[i] <<" ";
    }
}

int main(int argc, const char * argv[]) {
    int arr[] = {1,56,2,2,35,3,3,93};
    int n = sizeof(arr)/sizeof(arr[0]);      //get the number of elements in array
    quicksort(arr, 0, n-1);
    printArray(arr, n);
    return 0;
}