hdu1071(积分求直线和抛物线构成的面积)

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直线方程y = k*x + d;

抛物线方程y = a(x-b)^2 + c；

然后对y1- y2求积分

代码如下：

#include<iostream>#include<algorithm>#include<cstring>#include<stack>#include<queue>#include<set>#include<map>#include<stdio.h>#include<stdlib.h>#include<ctype.h>#include<time.h>#include<math.h>#define inf 0x7fffffff#define eps 1e-9#define pi acos(-1.0)#define P system("pause")using namespace std;double a,b,c,k,d;double fun(double x){    return a*x*x*x/3 - x*x*(2*a*b+k)/2 + x*(a*b*b-d+c);}int main(){//freopen("input.txt","r",stdin);//freopen("output.txt","w",stdout);    int t;    scanf("%d",&t);    while(t--)    {        double x1,y1,x2,y2,x3,y3;        scanf("%lf%lf%lf%lf%lf%lf",&x1,&y1,&x2,&y2,&x3,&y3);        k = (y3-y2)/(x3-x2);        d = y2 - k*x2;        b = x1;        c = y1;        a = (y2-y1)/((x2-x1)*(x2-x1));        printf("%.2lf\n",fabs(fun(x3) - fun(x2)));    }    return 0;}

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