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</pre><pre name="code" class="cpp">#include<iostream>
#include<sstream>
#include<string>
#include<vector>
#include<list>
#include<set>
#include<map>
#include<stack>
#include<queue>
#include<algorithm>
#include<numeric>
#include<cmath>
#pragma warning(disable:4996)
using std::cin;
using std::cout;
using std::endl;
using std::stringstream;
using std::string;
using std::vector;
using std::list;
using std::pair;
using std::set;
using std::multiset;
using std::map;
using std::multimap;
using std::stack;
using std::queue;
using std::priority_queue;
class Point
{
public:
long double x, y;
Point() {}
Point(const long double &X, const long double &Y)
{
x = X;
y = Y;
}
};
class Line
{
public:
long double a, b, c;//ax+by=c
long double x_min, x_max, y_min, y_max;//直线的值域
Line() {}
Line(const Point &first, const Point &second)
{
x_min = std::min(first.x, second.x);
x_max = std::max(first.x, second.x);
y_min = std::min(first.y, second.y);
y_max = std::max(first.y, second.y);
if (first.x != second.x)//斜率式可行
{
b = 1;
a = -(first.y - second.y) / (first.x - second.x);
c = first.y + a*first.x;
}
else//k->无穷
{
b = 0;
a = 1;
c = first.x;
}
}
bool lineIntersected(const Line &line)//直线相交的判定
{
auto D = a*line.b - line.a*b;
if (D)
{
return true;
}
return false;
}
bool lineParallel(const Line&line)//判断两直线是否平行
{
auto D = a*line.b - line.a*b;
if (!D)
{
return true;
}
return false;
}
bool lineOverlapped(const Line&line)//判断两直线是否重合（平行的特例）
{
auto D = a*line.b - line.a*b;
auto Dx = c*line.b - line.c*b;
auto Dy = a*line.c - line.a*c;
if (!D&&!Dx&&!Dy)
{
return true;
}
return false;
}
long double fixed(long double value)
{
value *= (long double)1000000000000.0;
value += 0.5;
value = floor(value);
value /= (long double)1000000000000.0;
return value;
}
Point getIntersection(const Line&line)//行列式求两直线交点,要修正误差
{
auto D = a*line.b - line.a*b;
auto Dx = c*line.b - line.c*b;
auto Dy = a*line.c - line.a*c;
return{ fixed(Dx / D),fixed(Dy / D) };
}
bool segmentIntersected(const Line &line)
{
if (lineIntersected(line))
{
auto point = getIntersection(line);
if (point.x >= x_min&&point.x <= x_max
&&point.y >= y_min&&point.y <= y_max
&&point.x >= line.x_min&&point.x <= line.x_max
&&point.y >= line.y_min&&point.y <= line.y_max
)//交点在两线段的值域内
{
return true;
}
}
return false;
}
bool segmentOverlapped(const Line &line)
{
if (lineOverlapped(line))
{
if ((x_min <= line.x_max&&x_min >= line.x_min) || (x_max <= line.x_max&&x_max >= line.x_min))
{
return true;
}
}
return false;
}
};
class Rectangle
{
public:
long double left, right, top, bottom;
bool inRectangle(const Point &point)
{
if (point.x >= left&&point.x <= right&&point.y >= bottom&&point.y <= top)
{
return true;
}
return false;
}
};
int main()
{
//freopen("input.txt", "r", stdin);
//freopen("output.txt", "w", stdout);
int n;
while (cin >> n)
{
for (int i = 0; i < n; i++)
{
long double x1, y1, x2, y2;
cin >> x1 >> y1 >> x2 >> y2;
Rectangle rectangle;
cin >> rectangle.left >> rectangle.top >> rectangle.right >> rectangle.bottom;
if (rectangle.left > rectangle.right)
{
std::swap(rectangle.left, rectangle.right);
}
if (rectangle.bottom > rectangle.top)
{
std::swap(rectangle.bottom, rectangle.top);
}
if (rectangle.inRectangle({ x1,y1 }) || rectangle.inRectangle({ x2,y2 }))
{
//只要一个端点在矩形内，就有交点
cout << 'T' << endl;
}
else
{
Line line({ x1,y1 }, { x2,y2 });
vector<long double>segment(4);
segment[0] = rectangle.top;
segment[1] = rectangle.right;
segment[2] = rectangle.bottom;
segment[3] = rectangle.left;
bool flag = false;
for (int i = 0; i < 4; i++)
{
Line another({ segment[i],segment[(i + 1) % 4] }, { segment[(i + 1) % 4],segment[(i + 2) % 4] });
if (line.segmentIntersected(another)||line.lineOverlapped(another))
{
flag = true;
break;
}
}
if (flag)
{
cout << 'T' << endl;
}
else
{
cout << 'F' << endl;
}
}
}
}
return 0;
}
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原文地址：http://blog.csdn.net/cxy7tv/article/details/51347465
