hdu 2073 无限的路

#include<stdio.h>
#include<math.h>
double answer(int x,int y)
{
double t=sqrt(2);
double ans=0;
int i;
for(i=1;i<x+y;i++)
ans+=t*i;
ans+=t*x;
for(i=0;i<x+y;i++)
ans+=sqrt(i*i+(i+1)*(i+1));
return ans;
}

int main()
{
int N;
int x1,y1,x2,y2;
scanf("%d",&N);
while(N--)
{
scanf("%d%d%d%d",&x1,&y1,&x2,&y2);
printf("%.3lf\n",fabs(answer(x1,y1)-answer(x2,y2)));
}
return 0;
}