poj 2540 Hotter Colder-白红宇

poj 2540 Hotter Colder

阅读量：5911 次

发布时间：2019-06-19

本文共 2146 字，大约阅读时间需要 7 分钟。

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                 #define LL long longusing namespace std;class Point{public: double x,y; Point(){} Point( double xx , double yy ):x(xx),y(yy){}}p[124],q[124];void Init( Point &pre ){ pre = Point( 0 , 0 ); p[1] = Point( 0 , 0 ); p[2] = Point( 0 , 10 ); p[3] = Point( 10 , 10 ); p[4] = Point( 10 , 0 ); p[5] = p[1]; p[0] = p[4];}void Get_line( Point pre, Point cur , double &A, double &B, double &C){ Point a = Point( (pre.x + cur.x)/2.0 , ( pre.y + cur.y )/2.0 ); A = cur.x - pre.x; B = cur.y - pre.y; C = -A*a.x - B*a.y; }Point Get_point( Point a,Point b, double A,double B,double C ){ double u = fabs( A*a.x + B*a.y + C ); double v = fabs( A*b.x + B*b.y + C ); Point ans; ans.x = ( u*b.x + v*a.x )/(u+v); ans.y = ( u*b.y + v*a.y )/(u+v); return ans; }int Solve( int n ,double A,double B,double C){ int m = 0; for( int i = 1 ; i <= n ; i ++ ) { if( A*p[i].x + B*p[i].y + C > 0 ) q[++m] = p[i]; else { if( A*p[i-1].x + B*p[i-1].y + C > 0 ) q[++m] = Get_point( p[i] , p[i-1] ,A,B,C ); if(A*p[i+1].x + B*p[i+1].y + C > 0) q[++m] = Get_point( p[i] , p[i+1] ,A,B,C ); } } for( int i =1 ; i <= m; i ++ ) p[i] = q[i]; p[m+1] = p[1]; p[0] = p[m]; return m;}double Area( int n ){ double area=0; p[n+1] = p[1]; for( int i = 1; i <= n ; i ++ ) area += p[i].x*p[i+1].y - p[i].y*p[i+1].x; return fabs( area/2.0 ); }int main( ){ Point pre,cur; bool flag = false; char str[12]; double A,B,C; int n = 4; Init( pre ); while( scanf( "%lf%lf%s",&cur.x,&cur.y,str )==3 ) { if( !flag ) { Get_line( pre , cur , A,B,C ); if( str[0] == 'C' ) { if( A*pre.x + B*pre.y + C < 0 ) { A = -A; B = -B ; C = -C; } } else if( str[0] == 'H' ) { if( A*cur.x + B*cur.y + C < 0 ) { A = -A ; B = -B ; C = -C; } } else {flag = true;puts( "0.00" );continue;} n = Solve( n ,A ,B ,C ); printf("%.2f\n",Area( n ) ); pre = cur; } else puts( "0.00" ); } //system( "pause" ); return 0;}