快速排序的几种实现

来源：互联网发布：纽昂司软件成都分公司编辑：程序博客网时间：2024/06/05 20:39

通过分而治之的思想，将待排序的序列划分为两个子序列，并分别进行排序。

#include <iostream>#include <utility>#include <cstdlib>using namespace std;int partition(int *a, int left, int right){    int pivot = a[right];    int i = left - 1;    for(int j = left; j < right; j ++)        if(a[j] <= pivot) swap(a[++i], a[j]);    swap(a[i+1], a[right]);    return i+1;}int partition_hoare(int *a, int left, int right){    int pivot = a[left];    int i = left - 1, j = right + 1;    while(1){        do{j --;} while(a[j] > pivot);        do{i ++;} while(a[i] < pivot);        if(i < j) swap(a[i], a[j]);        else return j;    }}int partition_hoare_update(int *a, int left, int right){    int pivot = a[left];    int i = left, j = right;    while(i < j){        while(i < j && a[j] >= pivot) j --;        if(i < j) a[i++] = a[j];        while(i < j && a[i] <= pivot) i ++;        if(i < j) a[j--] = a[i];    }    a[j] = pivot;    return j;}void quick_sort(int *a, int left, int right){    if(left < right){        //int p = partition(a, left, right);        int p = partition_hoare(a, left, right);        quick_sort(a, left, p-1);        quick_sort(a, p+1, right);    }}int main(){    int n = 1000000;    int *a = new int[n];    for(int i = 0; i < n; i ++) a[i] = rand();    quick_sort(a, 0, n-1);    //validate    for(int i = 0; i < n; i ++)        if(i + 1 < n && a[i] > a[i + 1]){            cout << "error" << endl;            break;        }    return 0;}

0 0