向量叉积的应用——正反画画

1

解题思路

解题思路涉及的向量积相关知识

c++实现

#include<iostream>
#include<vector>

using namespace std;

struct TrianglePoint {
	int x;
	int y;
};

int momentForce(TrianglePoint A, TrianglePoint B, TrianglePoint C)
{
	//AB向量：(B.x-A.x, B.y-A.y)，AC向量：(C.x-A.x, C.y-A.y)
	int result = (B.x - A.x) * (C.x - A.y) - (C.x - A.x) * (B.y-A.y);
	return result;
}

int main()
{
	int n;
	cin >> n;
	TrianglePoint A, B, C;
	vector<int> results;
	while (n)
	{
		cin >> A.x >> A.y >> B.x >> B.y >> C.x >> C.y;
		int result = momentForce(A,B,C);
		results.push_back(result);
		n--;
	}
	for (int i = 0; i < results.size(); i++)
	{
		if (results[i] > 0)
		{
			cout<<"Counterclockwise"<<endl;
		}
		else
		{
			cout << "Clockwise" << endl;
		}
	}
	return 0;
}