#include<stdio.h>
#include<stdlib.h>
#define YES 1
#define NO 0
void SWAP(int x,int y) {int t;t=x;x=y;y=t;}
void ORDER2(int x,int y) {if(x>y) SWAP(x,y);}
void ORDER3(int x,int y,int z) {ORDER2(x,y),ORDER2(x,z),ORDER2(y,z);}
    void quicksort(int *left,int *right);
    int pivot(int *left,int *right,int *pivot_pos);
    int *partition(int *left,int *right,int pivot);
int main()
{

    int i,a[1000],N;
    scanf("%d",&N);
    for(i=0;i<N;i++)
    {
        scanf("%d",&a[i]);
    }
    quicksort(a,a+N-1);
    for(i=0;i<N;i++)
        printf("%d\t",a[i]);
    return 0;
}

void quicksor(int *left,int *right)
{
    int *p,pivot_p;
    if(pivot(left,right,&pivot_p))
    {
        p=partition(left,right,pivot_p);
        quicksort(left,p-1);
        quicksort(p,right);
    }
}
int pivot(int *left,int *right,int *pivot_pos)
{
    int a,b,c,*p;
    a=*left;
    b=*(left+(right-left)/2);
    c=*right;
    ORDER3(a,b,c);
    if(a<b)
    {
        *pivot_pos=b;
        return YES;
    }
    else if(b<c)
    {
        *pivot_pos=c;
        return YES;
    }
    else
        for(p=left+1;p<=right;p++)
            if(*p!=*left)
            {
                *pivot_pos=(*p<*left)?*left:*p;
                return YES;
            }
            return NO;
}
int *partition(int *left,int *right,int pivot)
{
    while(left<=right)
    {
        while(*left<pivot)
            left++;
        while(*right>=pivot)
            right--;
        if(left<right)
        {
            SWAP(*left,*right);
            left++;
            right--;
        }
    }
    return left;
}

运行一下，一个错误，是：
Linking...
试一试.obj : error LNK2001: unresolved external symbol "void __cdecl quicksort(int *,int *)" (?quicksort@@YAXPAH0@Z)
Debug/试一试.exe : fatal error LNK1120: 1 unresolved externals
执行 link.exe 时出错.

完全不知道为什么错了。