杭电acm1071

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

一条抛物线跟一条直线围成一个图形，给出两个交点和曲线最高点的坐标，求出面积，自己退出各个公式的系数，然后定积分求出结果

View Code

 1 #include<stdio.h>
 2 int main()
 3 {
 4  int t;
 5  double x1,x2,x3,y1,y2,y3,a,b,c,k,h,s;
 6  scanf("%d",&t);
 7  while(t--)
 8    {
 9     scanf("%lf%lf",&x1,&y1);
10     scanf("%lf%lf",&x2,&y2);
11     scanf("%lf%lf",&x3,&y3);
12         k=(y3-y2)/(x3-x2);
13         h=y2-k*x2;//直线斜截式的斜率和截距
14         a=(((y2-y1)/(x2-x1))-((y3-y2)/(x3-x2)))/(x1-x3);
15         b=((y2-y1)/(x2-x1))-(a*(x1+x2));
16         c=y3-(a*x3*x3+b*x3);//抛物线的a，b，c
17         s=((a/3)*x3*x3*x3+((b-k)/2)*x3*x3+(c-h)*x3)-((a/3)*x2*x2*x2+((b-k)/2)*x2*x2+(c-h)*x2);//定积分求面积
18     printf("%.2lf\n",s);
19    }
20    return 0;
21 }