思路就是用顶点式求抛物线的方程，然后再再求出其原函数，积分减去梯形面积即可

1 #include 
     
        2 #include 
      
         3 #include 
       
          4  5 double a, b, c,  x1, x2, x3, p1, p2, p3;  6  7 double  fun (double  x )  8 {  9     return (1.0 / 3 ) * a * ( x - x1 ) * (x - x1 ) * (x - x1 ) + p1 * x; 10 } 11 12 int main( ) 13 {
    14     int T, i; 15     scanf("%d", &T); 16     while (T--) 17     { // printf("%d\n",T); 18     19         scanf("%lf %lf %lf %lf %lf %lf",&x1, &p1, &x2, &p2, &x3, &p3); 20         a = (p2 - p1) /( (x2 - x1) * (x2 - x1) ); 21         b = (p2 + p3 ) * ( x3 - x2 ) /  2.0; 22         c = fun ( x3 ) - fun ( x2 ) - b; 23         printf("%.2lf\n",c); 24         //system("pause"); 25     } 26     return 0; 27 }