uva 2453 凸包

#include <bits/stdc++.h>
using namespace std;
const int maxn = 1000 + 10;
const double PI = acos(-1);
int n, T;
double L;
struct Point
{
	double x, y;
	Point(double x = 0, double y = 0): x(x), y(y) {}
};
typedef Point Vector;
typedef vector<Point> Polygon;
Vector operator +(Vector A, Vector B)//
{
	return Vector(A.x + B.x, A.y + B.y);
}
Vector operator -(Point A, Point B)//
{
	return Vector(A.x - B.x , A.y - B.y);
}
Vector operator *(Vector A, double p)//
{
	return Vector(A.x * p, A.y * p);
}
Vector operator /(Vector A, double p)//
{
	return Vector(A.x / p, A.y / p);
}
bool operator <(const Point &a, const Point &b)//
{
	return a.x < b.x || (a.x == b.x && a.y < b.y);
}
const double eps = 1e-10;
int dcmp(double x)//
{
	if (fabs(x) < eps) return 0;
	else return x < 0 ? -1 : 1;
}
bool operator ==(const Point &a, const Point &b)//
{
	return dcmp(a.x - b.x) == 0 && dcmp(a.y - b.y) == 0;
}
Point read_point()
{
	double X, Y;
	scanf("%lf%lf", &X, &Y);
	return Point(X, Y);
}
double Dot(Vector A, Vector B)//
{
	return A.x * B.x + A.y * B.y;
}
double Length(Vector A)//
{
	return sqrt(Dot(A, A));
}
double Cross(Vector A, Vector B)//
{
	return A.x * B.y - A.y * B.x;
}
vector<Point> ConvexHull(vector<Point>& p)
{
	sort(p.begin(), p.end());
	p.erase(unique(p.begin(), p.end()), p.end());
	int n = p.size();
	int m = 0;
	vector<Point> ch(n + 1);
	for (int i = 0; i < n; i++)
	{
		while (m > 1 && Cross(ch[m - 1] - ch[m - 2], p[i] - ch[m - 2]) <= 0) m--;
		ch[m++] = p[i];
	}
	int k = m;
	for (int i = n - 2; i >= 0; i--)
	{
		while (m > k && Cross(ch[m - 1] - ch[m - 2], p[i] - ch[m - 2]) <= 0) m--;
		ch[m++] = p[i];
	}
	if (n > 1) m--;
	ch.resize(m);
	return ch;
}
Polygon P;
int main(int argc, char const *argv[])
{
	scanf("%d", &T);
	while (T--)
	{
		scanf("%d%lf", &n, &L);
		for (int i = 0; i < n; i++)
			P.push_back(read_point());
		Polygon newp = ConvexHull(P);
		int lenn = newp.size();
		newp.push_back(newp.front());
		double ans = 0;
		for (int i = 0; i < lenn; i++)
			ans += Length(newp[i] - newp[i + 1]);
		ans += 2.0 * PI * L;
		printf("%.0lf\n", ans);
		if (T) printf("\n");
	}
	return 0;
}

所有角加起来为360度，其余纯模板