快速排序的一种实现

#include <stdio.h>

void print_arry(const int *str, int length)
{
    int i;

    for (i = 0; i < length; i++)
    {
        printf("%4d", str[i]);
    }
    printf("\n");

    return;
}

void swap(int *arry, int left, int right)
{
    int tmpval;

    tmpval = arry[left];
    arry[left] = arry[right];
    arry[right] = tmpval;

    return;
}

int partition(int *arry, int left, int right, int pivotIndex)
{
    int i;
    int tmpval;
    int index;

    tmpval = arry[pivotIndex];
    index = left;

    swap(arry, left, pivotIndex);

    for (i = left+1; i <= right; i++)
    {
        if (arry[i] < tmpval)
        {
            index++;
            swap(arry, index, i);
        }
    }

    swap(arry, left, index);

    return index;
}

int select_pivotIndex(int *arry, int left ,int right)
{
    return (left + (right - left)/2);
}

void quick_sort(int *arry, int left, int right)
{
    int pivotIndex = 0;
    int pivotNewIndex = 0;

    if (left < right)
    {
        pivotIndex = select_pivotIndex(arry, left, right);
        pivotNewIndex = partition(arry, left, right, pivotIndex);

        quick_sort(arry, left, pivotNewIndex-1);
        quick_sort(arry, pivotNewIndex+1, right);
    }

    return;
}


int main(void)
{
    int length;
    int arry[] = {1, 10, 30, 40 ,2, 8, 50, 70};

    length = sizeof(arry)/sizeof(arry[0]);

    print_arry(arry, length);
    quick_sort(arry, 0, length-1);
    print_arry(arry, length);

    return 0;
}