用c语言写一个程序，要求使用安德鲁算法求出一个点集的凸包

下面是一个使用 C 语言实现安德鲁算法求出点集凸包的示例代码：

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

#define MAX_POINTS 100
#define MAX_HULL_POINTS MAX_POINTS

typedef struct point
{
    int x, y;
} Point;

Point hull[MAX_HULL_POINTS];

// 计算两点之间的距离
double distance(Point A, Point B)
{
    return sqrt((A.x - B.x) * (A.x - B.x) + (A.y - B.y) * (A.y - B.y));
}

// 判断三点关系，以 p2 为基点，返回 p1 和 p3 相对于 p2 的位置关系
int orientation(Point p1, Point p2, Point p3)
{
    int val = (p3.y - p2.y) * (p2.x - p1.x) - (p2.y - p1.y) * (p3.x - p2.x);
    if (val == 0) return 0;
    return (val > 0) ? 1 : 2;
}

// 寻找凸包上的点
void andrew(Point points[], int n)
{
    int l = 0;
    for (int i = 1; i < n; i++)
        if (points[i].y < points[l].y || (points[i].y == points[l].y && points[i].x < points[l].x))
            l = i;
    Point temp = points[0];
    points[0] = points[l];
    points[l] = temp;
    Point p1, p2;
    p1 = points[0];
    for (int i = 1; i < n; i++)
    {
        p2 = points[i];
        while (i < n - 1 && orientation(p1, p2, points[i + 1]) == 0)
            p2 = points[++i];
        hull[++l] = p2;
        p1 = p2;
    }
    int m = 1;
    for (int i = n - 2; i >= 0; i--)
    {
        p2 = points[i];
        while (i > 0 && orientation(hull[m - 1], hull[m], p2) == 0)
            m--;
        hull[++m] = p2;
    }
    int count = m;
    printf("凸包上的点有：\n");
    for (int i = 0; i < count; i++)
        printf("(%d