【HDOJ】1071 The area

数学题，先求抛物线和直线的系数，再利用积分公式求面积。

 #include <stdio.h>
 #include <math.h>

 int main() {
     double x1, x2, x3, y1, y2, y3;
     double a, b, c, k, m;
     double s1, s2;
     int case_n;

     scanf("%d", &case_n);

     while (case_n--) {
         scanf("%lf%lf%lf%lf%lf%lf", &x1,&y1, &x2,&y2, &x3,&y3);
         a = (y2-y1) / pow(x2-x1, );
         b = -*a*x1;
         c = a*x1*x1+y1;
         k = (y2-y3) / (x2-x3);
         m = y3 - k*x3;
         s1 = a*pow(x2, )/ + (b-k)*x2*x2/ + (c-m)*x2;
         s2 = a*pow(x3, )/ + (b-k)*x3*x3/ + (c-m)*x3;
         printf("%.2lf\n", s2-s1);
     }

     return ;
 }