判断一个点是否在三角形内部

在博主的程序中存在小bug，不过博主的讲解是不错的
点击打开链接
#include<cstdio>
#include<iostream>
#include<algorithm>
#include<cmath>
#include<cstring>
#include<stack>
#include<queue>
#include<map>
using namespace std;
typedef long long LL;
class Vector2d//向量类
{
public:
double x_;
double y_;
public:

//构造函数
Vector2d(double x,double y)
{
x_=x;
y_=y;
}
Vector2d():x_(0),y_(0){}

//赋值函数,使用的原因是为了在算法验证中降低内存
Vector2d init(double x,double y)
{
x_=x;
y_=y;
}

//二维向量叉乘
double crossProduct(const Vector2d vec)
{
return x_*vec.y_-y_*vec.x_;
}

//二维向量减法,也可以作为求两点之间的向量
Vector2d Minus(const Vector2d vec)const
{
return Vector2d(x_-vec.x_,y_-vec.y_);
}
};
class Triangle//三角形类
{
private:
Vector2d pointA_,pointB_,pointC_;

public:

//三角形构造函数
Triangle(Vector2d point1,Vector2d point2,Vector2d point3)
:pointA_(point1),pointB_(point2),pointC_(point3){}

//pointP为所判断的点
bool isPointInTriangle(const Vector2d pointP)
{
//点也是向量，点差即为向量差可以求出两个点组成的向量
Vector2d PA=pointA_.Minus(pointP);
Vector2d PB=pointB_.Minus(pointP);
Vector2d PC=pointC_.Minus(pointP);
double t1=PA.crossProduct(PB);
double t2=PB.crossProduct(PC);
double t3=PC.crossProduct(PA);
return (t1*t2>=0)&&(t1*t3>=0)&&(t2*t3>=0);
}

};
int main()
{
Triangle tri(Vector2d(0,0),Vector2d(0,100),Vector2d(200,0));
int x,y;
Vector2d point;
while(scanf("%d%d",&x,&y)!=EOF)
{
point.init(x,y);
cout<<tri.isPointInTriangle(point)<<endl;
}

return 0;
}