202006-1 线性分类器
思路：数学问题中的判断点与直线位置关系

#include<iostream>
#include<vector>
using namespace std;

typedef struct point {
	int x;
	int y;
}P;
typedef struct line {
	int k0, k1, k2;
}L;

bool Classify(vector<P> A, vector<P> B, L line);//判断某条直线是否满足条件

int main()
{
	vector<P> A, B;
	vector<L> lines;
	int n, m; cin >> n >> m;
	for (int i = 0; i < n; i++)
	{
		P p;
		char ch;
		cin >> p.x >> p.y >> ch;
		if (ch == 'A') A.push_back(p);
		else B.push_back(p);
	}
	for (int i = 0; i < m; i++)
	{
		L l;
		cin >> l.k0 >> l.k1 >> l.k2;
		lines.push_back(l);
	}
	for (int i = 0; i < m; i++)
		if (Classify(A, B,lines[i])) cout << "Yes" << endl;
		else cout << "No" << endl;


	return 0;
}

bool Classify(vector<P> A, vector<P> B, L line)
{
	int A_cnt = 0, B_cnt = 0;
	for (int i = 0; i < A.size(); i++)
	{
		if (line.k0 + line.k1 * A[i].x + line.k2 * A[i].y > 0) A_cnt++;		
	}
	for (int i = 0; i < B.size(); i++)
	{
		if (line.k0 + line.k1 * B[i].x + line.k2 * B[i].y > 0) B_cnt++;
	}
	if((A_cnt==A.size()&&B_cnt==0)||(B_cnt==B.size()&&A_cnt==0))//A和B在直线两侧的情况
		return true;
	else return false;
}