poj1410巧妙变成直线与线段相交

这题粗看还以为是线段与线段相交，但是题目要求，线段完全在矩形内也是算相交。所以可以变成目标线段a所在的直线与矩形的各个线段相交问题，然后再看该线段a是否在矩形范围内。

[cpp]
#include <iostream>
using namespace std;

struct Point
{
    Point()
    {
        x=0.0f;
        y=0.0f;
    }

    Point(double tx,double ty)
    {
        x=tx;
        y=ty;
    }

    double x,y;
};

struct Segment
{
    Point point1,point2;
};

double Min(double a,double b)
{
    if(a<b)
        return a;
    else
        return b;
}

double Max(double a,double b)
{
    if(a<b)
        return b;
    else
        return a;
}

double CrossProduct(Point vec1,Point vec2)
{
    return (vec1.x*vec2.y)-(vec1.y*vec2.x);
}

//Calculate the crossproduct of (p2-p1)*(p3-p1)
double Direction(Point point1,Point point2,Point point3)
{
    Point vec1;
    vec1.x=point2.x-point1.x;
    vec1.y=point2.y-point1.y;

    Point vec2;
    vec2.x=point3.x-point1.x;
    vec2.y=point3.y-point1.y;

    return CrossProduct(vec1,vec2);
}

//See if line interact the segment.
bool LineInteractSegment(Segment line,Segment seg)
{
    Point vec1;
    vec1.x=line.point2.x-line.point1.x;
    vec1.y=line.point2.y-line.point2.y;

    Point vec2;
    vec2.x=seg.point2.x-seg.point1.x;
    vec2.y=seg.point2.y-seg.point2.y;

    double cross1=CrossProduct(
         Point(line.point2.x-line.point1.x,line.point2.y-line.point1.y ),
         Point(seg.point1.x-line.point1.x,seg.point1.y-line.point1.y));

    double cross2=CrossProduct(
         Point(line.point2.x-line.point1.x,line.point2.y-line.point1.y ),
         Point(seg.point2.x-line.point1.x,seg.point2.y-line.point1.y));

    if(cross1*cross2<=0)
        return true;
    else
        return false;
}

bool SegmentInRect(Segment seg,Point leftTopPoint,Point rightBottomPoint )
{
    double minX=Min(seg.point1.x,seg.point2.x);
    double maxX=Max(seg.point1.x,seg.point2.x);

    double minY=Min(seg.point1.y,seg.point2.y);
    double maxY=Max(seg.point1.y,seg.point2.y);

    if(minX>rightBottomPoint.x || maxX<leftTopPoint.x)
    {
        return false;
    }
    else
    {
        if(minY>leftTopPoint.y || maxY<rightBottomPoint.y)
        {
            return false;
        }
        else
        {
            return true;
        }
    }
}

void SwapData(double& a,double& b)
{
    double c=a;
    a=b;
    b=c;
    return;
}

int main()
{
    bool HaveInteraction=false;
    Segment seg;
    Segment rectSeg[4];
    double leftTopX,leftTopY,rightBottomX,rightBottomY;

    int tCase;
    //cin>>tCase;
    scanf("%d",&tCase);
    while(tCase>0)
    {
        tCase--;

        //cin>>seg.point1.x>>seg.point1.y>>seg.point2.x>>seg.point2.y;
        scanf("%lf%lf%lf%lf",&seg.point1.x,&seg.point1.y,&seg.point2.x,&seg.point2.y);

        //cin>>leftTopX>>leftTopY>>rightBottomX>>rightBottomY;
        scanf("%lf%lf%lf%lf",&leftTopX,&leftTopY,&rightBottomX,&rightBottomY);

        if(leftTopX>rightBottomX)
            SwapData(leftTopX,rightBottomX);
        if(rightBottomY>leftTopY)
            SwapData(rightBottomY,leftTopY);

        //start from | ,take turn in clockwise.
        rectSeg[0].point1= Point(leftTopX,rightBottomY);
        rectSeg[0].point2= Point(leftTopX,leftTopY);

        rectSeg[1].point1= Point(leftTopX,leftTopY);
        rectSeg[1].point2= Point(rightBottomX,leftTopY);

        rectSeg[2].point1= Point(rightBottomX,leftTopY);
        rectSeg[2].point2= Point(rightBottomX,rightBottomY);

        rectSeg[3].point1= Point(rightBottomX,rightBottomY);
        rectSeg[3].point2= Point(leftTopX,rightBottomY);

&n

补充：软件开发 , C++ ,