1071—The area

题目来源：http://acm.hdu.edu.cn/showproblem.php?pid=1071

经验教训：纯数学题~~~

我的代码（抛物线作于原点会更好做点~~）

#include<stdio.h>#include<string.h>#include<stdlib.h>int main(){int t;double x1,x2,x3,y1,y2,y3;scanf("%d",&t);int i;for(i=0;i<t;i++){scanf("%lf%lf",&x1,&y1);scanf("%lf%lf",&x2,&y2);scanf("%lf%lf",&x3,&y3);double k=0;double a,b,c,s1,s2,s;//a=(y2-y3)/(x2*x2-x3*x3-2*x1*x2+2*x1*x3);a=(y2-y1)/((x2-x1)*(x2-x1));b=-2.0*a*x1;c=y1-a*x1*x1-b*x1;k=(y3-y2)/(x3-x2);s1=1.0/3*a*x3*x3*x3+1.0/2*b*x3*x3+c*x3-1.0/2*k*x3*x3+(k*x2-y2)*x3;s2=1.0/3*a*x2*x2*x2+1.0/2*b*x2*x2+c*x2-1.0/2*k*x2*x2+(k*x2-y2)*x2;s=s1-s2;printf("%.2lf\n",s);}return 0;}