快排

#include <stdio.h>
#include <stdlib.h>

#define random(x) (rand()%x)

/*
 * xiaoyang 2011-9-22
 * sort algrithms
 */
void config(int* data, int len)
{
    int i = 0;
    srand((int)time(0));

    for(i = 0; i < len; i++){
        data[i] = random(2000);
    }
}

void print(int* data,int len)
{
    int i = 0;
    printf("---------------\n");
    for(i = 0; i < len; i++){
        printf("%d ",data[i]);
        if(i%20 == 19){
            printf("\n");
        }
    }
}

void swapx(int *data, int x, int y)
{
    int tmp = data[x];
    data[x] = data[y];
    data[y] = tmp;
}

/*
 * quick sort, partition
 */
int quick_sort_parti(int* data,int begin,int end)
{
    int x = data[begin];
    int lbegin = begin+1;
    int pos = begin;
    int tmp = 0;

    if(begin+1 >= end)
        return 0;

    /*保证判断元素的变化*/
    swapx(data,begin,end-1);
    x = data[begin];

    for(pos=begin+1; pos < end; pos++){
        if(data[pos] <= x){
            swapx(data,lbegin,pos);
            lbegin++;
        }else{

        }
    }

    /*保证切分的两部分都有元素*/
    if( (lbegin-begin) >= 1 ){
        swapx(data,begin,lbegin-1);
    }

    lbegin--;
    return lbegin;
}

void quick_sort(int* data,int begin,int end)
{
    int mid;

    if(begin+1 >= end)
        return ;

    mid = quick_sort_parti(data,begin,end);
    //printf("\n[%d,%d],mid=%d\n",begin,end,mid);
    //print(data,end-begin);

    quick_sort(data,begin,mid);
    //printf("\n[%d,%d]\n",begin,mid-1);
    //print(data,mid-1-begin);

    quick_sort(data,mid,end);
    //printf("\n[%d,%d]\n",mid,end);
    //print(data,end-mid);
}

/*
 * main
 */
int main()
{
    const int count = 100;
    int data[count];
    config(data,count);
    print(data,count);

    printf("\nbegin\n---------------\n");
    quick_sort(data,0,count);
    printf("\nend\n---------------\n");
    print(data,count);

    return 0;
}