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  • Pizza Cutting

    我心态崩了。
    吃完饭回来,『哇这个圆与矩形交到底怎么求啊???』,顿了一秒,
    嗯??这不是傻逼板子题吗?
    然后粘上了我圆和三角形交的板子。1A。
    mxy到底有什么用啊?
    这他妈这么傻逼的板子题。。我为什么四个小时都没意识到这是板子题。
    这种题还能wa?这怎么wa啊??

    #include <bits/stdc++.h>
    #define mp make_pair
    #define fi first
    #define se second
    #define pb push_back
    using namespace std;
    typedef double db;
    const int maxn = 4e5+5;
    const db eps=1e-6;
    const db pi=acos(-1);
    int sign(db k){
        if (k>eps) return 1; else if (k<-eps) return -1; return 0;
    }
    int cmp(db k1,db k2){return sign(k1-k2);}
    int inmid(db k1,db k2,db k3){return sign(k1-k3)*sign(k2-k3)<=0;}// k3 在 [k1,k2] 内
    struct point{
        db x,y;
        point operator + (const point &k1) const{return (point){k1.x+x,k1.y+y};}
        point operator - (const point &k1) const{return (point){x-k1.x,y-k1.y};}
        point operator * (db k1) const{return (point){x*k1,y*k1};}
        point operator / (db k1) const{return (point){x/k1,y/k1};}
        int operator == (const point &k1) const{return cmp(x,k1.x)==0&&cmp(y,k1.y)==0;}
        // 逆时针旋转
        point turn(db k1){return (point){x*cos(k1)-y*sin(k1),x*sin(k1)+y*cos(k1)};}
        point turn90(){return (point){-y,x};}
        bool operator < (const point k1) const{
            int a=cmp(x,k1.x);
            if (a==-1) return 1; else if (a==1) return 0; else return cmp(y,k1.y)==-1;
        }
        db abs(){return sqrt(x*x+y*y);}
        db abs2(){return x*x+y*y;}
        db dis(point k1){return ((*this)-k1).abs();}
        point unit(){db w=abs(); return (point){x/w,y/w};}
        void scan(){double k1,k2; scanf("%lf%lf",&k1,&k2); x=k1; y=k2;}
        void print(){printf("%.11lf %.11lf
    ",x,y);}
        db getw(){return atan2(y,x);}
        point getdel(){if (sign(x)==-1||(sign(x)==0&&sign(y)==-1)) return (*this)*(-1); else return (*this);}
        int getP() const{return sign(y)==1||(sign(y)==0&&sign(x)==-1);}
    };
    int inmid(point k1,point k2,point k3){return inmid(k1.x,k2.x,k3.x)&&inmid(k1.y,k2.y,k3.y);}
    db cross(point k1,point k2){return k1.x*k2.y-k1.y*k2.x;}
    db dot(point k1,point k2){return k1.x*k2.x+k1.y*k2.y;}
    db rad(point k1,point k2){return atan2(cross(k1,k2),dot(k1,k2));}
    // -pi -> pi
    int compareangle (point k1,point k2){//极角排序+
        return k1.getP()<k2.getP()||(k1.getP()==k2.getP()&&sign(cross(k1,k2))>0);
    }
    point proj(point k1,point k2,point q){ // q 到直线 k1,k2 的投影
        point k=k2-k1;return k1+k*(dot(q-k1,k)/k.abs2());
    }
    point reflect(point k1,point k2,point q){return proj(k1,k2,q)*2-q;}
    int clockwise(point k1,point k2,point k3){// k1 k2 k3 逆时针 1 顺时针 -1 否则 0
        return sign(cross(k2-k1,k3-k1));
    }
    int checkLL(point k1,point k2,point k3,point k4){// 求直线 (L) 线段 (S)k1,k2 和 k3,k4 的交点
        return cmp(cross(k3-k1,k4-k1),cross(k3-k2,k4-k2))!=0;
    }
    point getLL(point k1,point k2,point k3,point k4){
        db w1=cross(k1-k3,k4-k3),w2=cross(k4-k3,k2-k3); return (k1*w2+k2*w1)/(w1+w2);
    }
    int intersect(db l1,db r1,db l2,db r2){
        if (l1>r1) swap(l1,r1); if (l2>r2) swap(l2,r2); return cmp(r1,l2)!=-1&&cmp(r2,l1)!=-1;
    }
    int checkSS(point k1,point k2,point k3,point k4){
        return intersect(k1.x,k2.x,k3.x,k4.x)&&intersect(k1.y,k2.y,k3.y,k4.y)&&
               sign(cross(k3-k1,k4-k1))*sign(cross(k3-k2,k4-k2))<=0&&
               sign(cross(k1-k3,k2-k3))*sign(cross(k1-k4,k2-k4))<=0;
    }
    db disSP(point k1,point k2,point q){
        point k3=proj(k1,k2,q);
        if (inmid(k1,k2,k3)) return q.dis(k3); else return min(q.dis(k1),q.dis(k2));
    }
    db disSS(point k1,point k2,point k3,point k4){
        if (checkSS(k1,k2,k3,k4)) return 0;
        else return min(min(disSP(k1,k2,k3),disSP(k1,k2,k4)),min(disSP(k3,k4,k1),disSP(k3,k4,k2)));
    }
    int onS(point k1,point k2,point q){return inmid(k1,k2,q)&&sign(cross(k1-q,k2-k1))==0;}
    struct circle{
        point o; db r;
        void scan(){o.scan(); scanf("%lf",&r);}
        int inside(point k){return cmp(r,o.dis(k));}
    };
    struct line{
        // p[0]->p[1]
        point p[2];
        line(point k1,point k2){p[0]=k1; p[1]=k2;}
        line(){}
        point& operator [] (int k){return p[k];}
        int include(point k){return sign(cross(p[1]-p[0],k-p[0]))>0;}
        point dir(){return p[1]-p[0];}
        line push(){ // 向外 ( 左手边 ) 平移 eps
            const db eps = 1e-6;
            point delta=(p[1]-p[0]).turn90().unit()*eps;
            return {p[0]-delta,p[1]-delta};
        }
    };
    point getLL(line k1,line k2){return getLL(k1[0],k1[1],k2[0],k2[1]);}
    vector<point> getCL(circle k1,point k2,point k3){ // 沿着 k2->k3 方向给出 , 相切给出两个
        point k=proj(k2,k3,k1.o); db d=k1.r*k1.r-(k-k1.o).abs2();
        if (sign(d)==-1) return {};
        point del=(k3-k2).unit()*sqrt(max((db)0.0,d)); return {k-del,k+del};
    }
    db getarea(circle k1,point k2,point k3){
        // 圆 k1 与三角形 k2 k3 k1.o 的有向面积交
        point k=k1.o; k1.o=k1.o-k; k2=k2-k; k3=k3-k;
        int pd1=k1.inside(k2),pd2=k1.inside(k3);
        vector<point>A=getCL(k1,k2,k3);
        if (pd1>=0){
            if (pd2>=0) return cross(k2,k3)/2;
            return k1.r*k1.r*rad(A[1],k3)/2+cross(k2,A[1])/2;
        } else if (pd2>=0){
            return k1.r*k1.r*rad(k2,A[0])/2+cross(A[0],k3)/2;
        }else{
            int pd=cmp(k1.r,disSP(k2,k3,k1.o));
            if (pd<=0) return k1.r*k1.r*rad(k2,k3)/2;
            return cross(A[0],A[1])/2+k1.r*k1.r*(rad(k2,A[0])+rad(A[1],k3))/2;
        }
    }
    db getarea(circle o,point k1,point k2,point k3){
        return abs(getarea(o,k1,k2)+getarea(o,k2,k3)+getarea(o,k3,k1));
    }
    db r,dx,dy,x,y,p,S;
    circle o;
    vector<db> all;
    void slove(point a,point b,point c,point d){//小矩形
        db s = getarea(o,a,b,c)+getarea(o,b,c,d);
        if(sign(s)>0){
            all.push_back(s);
    //        a.print();b.print();c.print();d.print();
    //        printf("%.11f
    
    
    
    ",s);
        }
    }
    int main(){
        scanf("%lf%lf%lf%lf%lf%lf",&r,&dx,&dy,&x,&y,&p);
        o.o={0, 0};o.r=r;S = dx*dy;
        x+=dx*10000;
        y+=dy*10000;
        while (x>-r)x-=dx;while (y>-r)y-=dy;
        db minx = x,miny = y;
        point n;
        for(db i=minx;i<r;i+=dx){
            for(db j=miny;j<r;j+=dy){
                n={i,j};
                slove(n,n+(point){dx,0},n+(point){0,dy},n+(point){dx,dy});
    
            }
        }
        db mx = *max_element(all.begin(),all.end());
        int ans=0;
    //    printf("%d
    ",(int)all.size());
    //    sort(all.begin(),all.end());
        for(auto x:all){
    //        printf("%.11f
    ",x);
            if(mx*p+eps>=x)ans++;
        }
        printf("%d
    ",ans);
    }
    
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  • 原文地址:https://www.cnblogs.com/MXang/p/11620391.html
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