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最新推荐文章于 2020-03-04 17:03:10 发布

zhengnanlee

最新推荐文章于 2020-03-04 17:03:10 发布

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分类专栏：计算几何学文章标签： ACM题解报告计算几何学

本文链接：https://blog.youkuaiyun.com/zhengnanlee/article/details/15524727

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复变函数考试真闹心！！！

水题不解释。

#include <iostream>
#include <vector>
#include <algorithm>
#include <math.h>
#include <stdio.h>

using namespace std;

#define eps 1e-8
#define zero(x) (((x)>0?(x):-(x))<eps)

struct point
{
    double x, y;
};

struct line
{
    point a, b;
    int index;
} temp;

double xmult(point p1, point p2, point p0)
{
    return (p1.x - p0.x)*(p2.y - p0.y) - (p2.x - p0.x)*(p1.y - p0.y);
}

int dots_inline(point p1, point p2, point p3)
{
    return zero(xmult(p1, p2, p3));
}

int same_side(point p1, point p2, line l)
{
    return xmult(l.a, p1, l.b)*xmult(l.a, p2, l.b)>eps;
}

int dot_online_in(point p, line l)
{
    return zero(xmult(p, l.a, l.b)) && (l.a.x - p.x)*(l.b.x - p.x)<eps && (l.a.y - p.y)*(l.b.y - p.y)<eps;
}

int intersect_in(line u, line v){
    if (!dots_inline(u.a, u.b, v.a) || !dots_inline(u.a, u.b, v.b))
        return !same_side(u.a, u.b, v) && !same_side(v.a, v.b, u);
    return dot_online_in(u.a, v) || dot_online_in(u.b, v) || dot_online_in(v.a, u) || dot_online_in(v.b, u);
}

bool judge(line t)
{
    return intersect_in(t, temp);
}

vector<line> v;

int main()
{
    int n;
    while (~scanf("%d", &n) && n)
    {
        v.clear();
        for (int i = 1; i <= n; i++)
        {
            scanf("%lf%lf%lf%lf", &temp.a.x, &temp.a.y, &temp.b.x, &temp.b.y);
            temp.index = i;
            v.erase(remove_if(v.begin(), v.end(), judge), v.end());
            v.push_back(temp);
        }
        cout << "Top sticks: ";
        for (vector<line>::iterator it = v.begin(); it != v.end(); it++)
        {
            cout << (*it).index;
            if (it != v.end() - 1)
                cout << ", ";
            else
                cout << "." << endl;
        }
    }
}