快速排序

无聊练习下快排：

非递归版（从大到小）：

#include <iostream>
#include <cstdio>
#include <ctime>
#include <cstdlib>

using namespace std;

int Stack[1024],top;

int solve(int *arr, int st, int ed)
{
    int tem = arr[st];
    while(st < ed)
    {
        while(st < ed && arr[ed] <= tem)
            ed --;
        arr[st] = arr[ed];
        while(st < ed && arr[st] >= tem)
            st ++;
        arr[ed] = arr[st];
    }
    arr[st] = tem;
    return st;
}

void QuickSort(int *arr, int st, int ed)
{
    if(st < ed)
    {
        int mid = solve(arr,st,ed);
        if(st < mid-1)
        {
            Stack[++top] = st;
            Stack[++top] = ed;
        }
        if(mid+1 < ed)
        {
            Stack[++top] = mid+1;
            Stack[++top] = ed;
        }
        while(top)
        {
            int high = Stack[top--];
            int low = Stack[top--];
            mid = solve(arr,low,high);
            if(low < mid-1)
            {
                Stack[++top] = low;
                Stack[++top] = mid-1;
            }
            if(mid + 1 < high)
            {
                Stack[++top] = mid+1;
                Stack[++top] = high;
            }
        }
    }
}

int main()
{
    int *array;
    int len;
    while(cin >> len)
    {
        array = new int [len+1];
        top = 0;
        srand((int)time(0));
        for(int i=1; i<=len; i++)
            array[i] = rand()%1024 + 1;
        int startTime = clock();
        QuickSort(array,1,len);
        int endTime = clock();
        printf("Sort Time: %d\n",endTime-startTime);
        for(int i=1; i<=len; i++)
            printf("%d ",array[i]);
        puts("");
        delete [] array;
        array = NULL;
    }
    return 0;
}

 

递归版（从小到大）：

void QuickSort(int *arr, int st, int ed)
{
    if(st < ed)
    {
        int low = st, high = ed;
        int tem = arr[st];
        while(low < high)
        {
            while(low < high && arr[high] >= tem)
                high --;
            arr[low] = arr[high];
            while(low < high && arr[low] <= tem)
                low ++;
            arr[high] = arr[low];
        }
        arr[low] = tem;
        QuickSort(arr,st,low-1);
        QuickSort(arr,low+1,ed);
    }
}