●UVA 10652 Board Wrapping

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題鏈：

https://vjudge.net/problem/UVA-10652

題解：

計算幾何，Andrew求凸包，

裸題。。。（數組開小了，還整了半天。。。）

代碼：

#include<cmath>#include<cstdio>#include<cstring>#include<iostream>#include<algorithm>#define MAXN 650using namespace std;const double eps=1e-8,Pi=acos(-1);int sign(double x){if(fabs(x)<=eps) return 0;return x<0?-1:1;}struct Point{double x,y;Point(double _x=0,double _y=0):x(_x),y(_y){}};typedef Point Vector;bool operator < (const Point A,const Point B){return sign(A.x-B.x)<0||(sign(A.x-B.x)==0&&sign(A.y-B.y)<0);}bool operator == (Point A,Point B){return sign(A.x-B.x)==0&&sign(A.y-B.y)==0;}Vector operator + (Vector A,Vector B){return Vector(A.x+B.x,A.y+B.y);}Vector operator - (Point A,Point B){return Vector(A.x-B.x,A.y-B.y);}double operator ^ (Vector A,Vector B){return A.x*B.y-A.y*B.x;}Point D[MAXN*4],C[MAXN*4];double torad(double deg){return deg/180*Pi;}//角度轉弧度Vector rotate(Vector A,double angle){//向量A逆時針旋轉angle（弧度）return Vector(A.x*cos(angle)-A.y*sin(angle),A.x*sin(angle)+A.y*cos(angle));}int Andrew(int dnt){int cnt=0,k=0;sort(D+1,D+dnt+1); dnt=unique(D+1,D+dnt+1)-D-1;for(int i=1;i<=dnt;i++){while(cnt>1&&((C[cnt]-C[cnt-1])^(D[i]-C[cnt-1]))<=0) cnt--;C[++cnt]=D[i];} k=cnt;for(int i=dnt-1;i>=1;i--){while(cnt>k&&((C[cnt]-C[cnt-1])^(D[i]-C[cnt-1]))<=0) cnt--;C[++cnt]=D[i];}return cnt;}double PolygonArea(int cnt){double area=0;for(int i=1;i<cnt;i++) area+=(C[i]^C[i+1])/2;return area;}int main(){double area1,area2,x,y,w,h,angle;int Case,N,dnt,cnt; scanf("%d",&Case);while(Case--){area1=area2=dnt=cnt=0;scanf("%d",&N);for(int i=1;i<=N;i++){scanf("%lf%lf%lf%lf%lf",&x,&y,&w,&h,&angle);angle=-torad(angle);D[++dnt]=Point(x,y)+rotate(Vector(w/2,h/2),angle);D[++dnt]=Point(x,y)+rotate(Vector(-w/2,h/2),angle);D[++dnt]=Point(x,y)+rotate(Vector(w/2,-h/2),angle);D[++dnt]=Point(x,y)+rotate(Vector(-w/2,-h/2),angle);area1+=w*h;}cnt=Andrew(dnt);//printf("%d\n",cnt);area2=PolygonArea(cnt);printf("%.1lf %%\n",area1*100/area2);}return 0;}

　　

●UVA 10652 Board Wrapping