整理了一下旋转卡壳的模板,把接口统一了一下
//#include<bits/stdc++.h> //#pragma comment(linker, "/STACK:1024000000,1024000000") #include<stdio.h> #include<algorithm> #include<queue> #include<string.h> #include<iostream> #include<math.h> #include<set> #include<map> #include<vector> #include<iomanip> using namespace std; const double pi=acos(-1.0); #define ll long long #define pb push_back #define sqr(a) ((a)*(a)) #define dis(a,b) sqrt(sqr(a.x-b.x)+sqr(a.y-b.y)) const double eps=1e-6; const int maxn=5e4+56; const int inf=0x3f3f3f3f; int n; int tot; //凸包上点数 struct Point{ double x,y; Point(){} Point(double x,double y):x(x),y(y){} }point[maxn],vertex[maxn]; bool cmp(Point a,Point b){ return(a.y<b.y||(a.y== b.y && a.x<b.x)); } double xmult(Point p1,Point p2,Point p3){ //p3p1,p3p2的夹角测试 return ( (p1.x-p3.x)*(p2.y-p3.y)-(p1.y-p3.y)*(p2.x-p3.x) ); } //正表示p1在p2的顺时针方向 int Andrew(){ //返回凸包顶点数 sort(point,point+n,cmp); int top=1; vertex[0]=point[0];vertex[1]=point[1]; for(int i=2;i<n;i++){ while(top && xmult(point[i],vertex[top],vertex[top-1])>eps)top--; vertex[++top]=point[i]; } int len=top; vertex[++top]=point[n-2]; for(int i=n-3;i>=0;i--){ while(top!=len && xmult(point[i],vertex[top],vertex[top-1])>eps)top--; vertex[++top]=point[i]; } return top; } double rotating_calipers_r(int n){ //返回最大直径 int q=1;double ans=0; vertex[n]=vertex[0]; for(int p=0;p<n;p++){ while(xmult(vertex[p+1],vertex[q+1],vertex[p])>xmult(vertex[p+1],vertex[q],vertex[p]))q=(q+1)%n; ans=max(ans,max(dis(vertex[p],vertex[q]),dis(vertex[p+1],vertex[q+1]))); //更新方法是为了处理p,p+1 // q,q+1这种平行状况 } return ans; } double rotating_calipers_s(int m){ //最大三角形面积 if(m==1||m==2)return 0; double ans=0; for(int i=0;i<m;i++){ int q=1; for(int j=i+1;j<m;j++){ while(xmult(vertex[j],vertex[q+1],vertex[i])>xmult(vertex[j],vertex[q],vertex[i]))q=(q+1)%m; ans=max(ans,xmult(vertex[i],vertex[j],vertex[q])); } } return ans/2.0; } int main(){ while(~scanf("%d",&n)){ for(int i=0;i<n;i++){ scanf("%lf%lf",&point[i].x,&point[i].y); } int m=Andrew(); printf("%.2lf ",rotating_calipers_s(m)); } }