1 #include<iostream>  2 #include <stdio.h>  3 #include <math.h>  4 #include<cstring>  5 #include<algorithm>  6 #define eps 1e-8  7 using namespace std;  8 const int MAXN=1550;  9 int m; 10 double r,tx,ty,ans; 11 int cCnt,curCnt;//此时cCnt为最终切割得到的多边形的顶点数、暂存顶点个数 12 struct point 13 { 14     double x,y; 15     point(double x=0,double y=0):x(x),y(y) {} 16 }; 17 point points[MAXN],p[MAXN],q[MAXN];//读入的多边形的顶点（顺时针）、p为存放最终切割得到的多边形顶点的数组、暂存核的顶点 18 void getline(point x,point y,double &a,double &b,double   &c) //两点x、y确定一条直线a、b、c为其系数 19 { 20     a = y.y - x.y; 21     b = x.x - y.x; 22     c = y.x * x.y - x.x * y.y; 23 } 24 void initial() 25 { 26     for(int i = 1; i <= m; ++i)p[i] = points[i]; 27     p[m+1] = p[1]; 28     p[0] = p[m]; 29     cCnt = m;//cCnt为最终切割得到的多边形的顶点数，将其初始化为多边形的顶点的个数 30 } 31 point intersect(point x,point y,double a,double b,double c) //求x、y形成的直线与已知直线a、b、c、的交点 32 { 33     //cout<<a<<" "<<b<<" "<<c<<endl; 34     double u = fabs(a * x.x + b * x.y + c); 35     double v = fabs(a * y.x + b * y.y + c); 36     // cout<<u<<" "<<v<<endl; 37     point pt; 38     pt.x=(x.x * v + y.x * u) / (u + v); 39     pt.y=(x.y * v + y.y * u) / (u + v);//cout<<pt.x<<" -"<<pt.y<<" "<<x.x<<" "<<y.x<<endl; 40     return  pt; 41 } 42 void cut(double a,double b ,double c) 43 { 44     curCnt = 0; 45     for(int i = 1; i <= cCnt; ++i) 46     { 47         if(a*p[i].x + b*p[i].y + c > -eps)q[++curCnt] = p[i]; 48         else 49         { 50             if(a*p[i-1].x + b*p[i-1].y + c > eps) 51             { 52                 q[++curCnt] = intersect(p[i-1],p[i],a,b,c); 53             } 54             if(a*p[i+1].x + b*p[i+1].y + c > eps) //原理同上 55             { 56                 q[++curCnt] = intersect(p[i],p[i+1],a,b,c); 57             } 58         } 59         //cout<<q[curCnt].x<<" --"<<q[curCnt].y<<" "<<i<<" "<<p[i].x<<" "<<p[i].y<<endl; 60     } 61     for(int i = 1; i <= curCnt; ++i)p[i] = q[i]; 62     p[curCnt+1] = q[1]; 63     p[0] = p[curCnt]; 64     cCnt = curCnt; 65 } 66 int dcmp(double x) 67 { 68     if(fabs(x)<eps) return 0; 69     return x<0?-1:1; 70 } 71 void solve(double x,double y,int flag) 72 { 73     double a,b,c; 74     if(flag == 1) 75     { 76         a = -2*x+2*tx,b = -2*y+2*ty,c = x*x+y*y-tx*tx-ty*ty; 77     } 78     else if(flag==2) 79     { 80         a = 2*x-2*tx,b = 2*y-2*ty,c = tx*tx+ty*ty-x*x-y*y; 81     } 82 //    if(dcmp(a)==0&&dcmp(b)==0&&dcmp(c)<=0) 83 //    { 84 //        ans = 0; 85 //        return ; 86 //    } 87     cut(a,b,c); 88 } 89 int main() 90 { 91     points[1] = point(0,0); 92     points[2] = point(0,10); 93     points[3] = point(10,10); 94     points[4] = point(10,0); 95     p[5] = p[1]; 96     m = 4; 97     tx = 0,ty=0; 98     char s[10]; 99     double x,y;100     initial();101     while(scanf("%lf%lf%s",&x,&y,s)!=EOF)102     {103         int flag;104         if(strcmp(s,"Colder")==0||strcmp(s,"Same")==0)solve(x,y,1);105         if(strcmp(s,"Hotter")==0||strcmp(s,"Same")==0)solve(x,y,2);106         tx = x,ty=y;107         double area = 0;108         for(int i = 1; i <= cCnt; ++i)109         {110             //cout<<p[i].x<<" "<<p[i].y<<endl;111             area += p[i].x * p[i + 1].y - p[i + 1].x * p[i].y;112         }113         area = fabs(area / 2.0);114         ans = area;115         printf("%.2f\n",ans);116     }117 }