This article is made by Jason-Cow.
Welcome to reprint.
But please post the article's address.
题意见白书，P272~273
把之前的板子拼起来就可以了
ans=(S(木板)*100/S(凸包))%
板子太长，先贴关键
求面积
db Area(D*R,int n){ db S=0.0; for(int i=1;i<n;i++)S+=Cross(R[i]-R[1],R[i+1]-R[1]); return S/2; }
int n,cnt=0;db S1=0.0; for(scanf("%d",&n);n--;){ db x,y,w,h,j,a; scanf("%lf%lf%lf%lf%lf",&x,&y,&w,&h,&j); D O(x,y);a=-Rad(j); R[++cnt]=O+Rotate(V(-w/2,-h/2),a); R[++cnt]=O+Rotate(V( w/2,-h/2),a); R[++cnt]=O+Rotate(V(-w/2, h/2),a); R[++cnt]=O+Rotate(V( w/2, h/2),a); S1+=w*h;
} int m=Andrew(R,cnt,A); db S2=Area(A,m); printf("%.1lf %%\n",S1*100.0/S2);
1 #include <algorithm> 2 #include <iostream> 3 #include <cstring> 4 #include <cstdlib> 5 #include <cstdio> 6 #include <vector> 7 #include <cmath> 8 #include <queue> 9 #include <map> 10 #include <set> 11 using namespace std; 12 #define sqr(x) ((x)*(x)) 13 #define RG register 14 #define op operator 15 #define IL inline 16 #define db double 17 #define bl bool 18 #define vo void 19 IL vo read(int&x){ 20 x=0;char c=getchar(),f=0; 21 while(c<'0'||c>'9'){if(c=='-')f=1;c=getchar();} 22 while(c>='0'&&c<='9')x=x*10+c-'0',c=getchar(); 23 if(f)x=-x; 24 } 25 const db pi=acos(-1.0),eps=1e-10; 26 struct D{ 27 db x,y; 28 D(db x=0.0,db y=0.0):x(x),y(y){} 29 }; 30 typedef D V; 31 bl op<(D A,D B){return A.x<B.x||(A.x==B.x&&A.y<B.y);} 32 V op+(V A,V B){return V(A.x+B.x,A.y+B.y);} 33 V op-(V A,V B){return V(A.x-B.x,A.y-B.y);} 34 V op*(V A,db N){return V(A.x*N,A.y*N);} 35 V op/(V A,db N){return V(A.x/N,A.y/N);} 36 37 38 db Ang(db x){return(x*180.0/pi);} 39 db Rad(db x){return(x*pi/180.0);} 40 V Rotate(V A,db a){return V(A.x*cos(a)-A.y*sin(a),A.x*sin(a)+A.y*cos(a));} 41 db Dis(D A,D B){return sqrt(sqr(A.x-B.x)+sqr(A.y-B.y));} 42 db Cross(V A,V B){return A.x*B.y-A.y*B.x;} 43 44 db Area(D*R,int n){ 45 db S=0.0; 46 for(int i=1;i<n;i++)S+=Cross(R[i]-R[1],R[i+1]-R[1]); 47 return S/2; 48 } 49 db Leng(D*R,int n){ 50 db C=0.0; 51 for(int i=2;i<=n;i++)C+=Dis(R[i],R[i-1]); 52 return C+Dis(R[n],R[1]); 53 } 54 55 int Andrew(D*R,int n,D*A){ 56 int m=0; 57 sort(R+1,R+n+1); 58 for(int i=1;i<=n;i++){ 59 while(m>=2 && Cross(A[m]-A[m-1],R[i]-A[m-1])<=0)m--; 60 A[++m]=R[i]; 61 } 62 int k=m; 63 for(int i=n-1;i>=1;i--){ 64 while(m>k && Cross(A[m]-A[m-1],R[i]-A[m-1])<=0)m--; 65 A[++m]=R[i]; 66 } 67 return n>1?m-1:m; 68 } 69 70 D GO; 71 bl acomp(D A,D B){ 72 db x=Cross(A-GO,B-GO); 73 if(x>0)return 1;if(x<0)return 0; 74 return Dis(GO,A)<Dis(GO,B); 75 } 76 77 int Graham(D*R,int n,D*A){ 78 for(int i=1;i<=n;i++){ 79 if(R[i].y<R[1].y)swap(R[i],R[1]); 80 else if(R[i].y==R[1].y&&R[i].x<R[1].x)swap(R[i],R[1]); 81 } 82 GO=R[1],sort(R+2,R+n+1,acomp); 83 int m=0;A[++m]=R[1],A[++m]=R[2]; 84 for(int i=3;i<=n;i++) 85 { 86 while(m>1 && Cross(A[m-1]-R[i],A[m]-R[i])<=0)m--; 87 A[++m]=R[i]; 88 } 89 return m; 90 } 91 const int maxn=(600<<2)+10; 92 D R[maxn],A[maxn]; 93 int main(){ 94 int T; 95 for(scanf("%d",&T);T--;){ 96 int n,cnt=0;db S1=0.0; 97 for(scanf("%d",&n);n--;){ 98 db x,y,w,h,j,a; 99 scanf("%lf%lf%lf%lf%lf",&x,&y,&w,&h,&j); 100 D O(x,y);a=-Rad(j); 101 R[++cnt]=O+Rotate(V(-w/2,-h/2),a); 102 R[++cnt]=O+Rotate(V( w/2,-h/2),a); 103 R[++cnt]=O+Rotate(V(-w/2, h/2),a); 104 R[++cnt]=O+Rotate(V( w/2, h/2),a); 105 S1+=w*h; 106 } 107 int m=Andrew(R,cnt,A); 108 db S2=Area(A,m); 109 printf("%.1lf %%\n",S1*100.0/S2); 110 } 111 return 0; 112 }