三分

CZ写的三分模板

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <math.h>
#define eps 1e-9
double a,b;
double getsum(double c)
{
    double p,sum = 0;
    p = (a+b+c)/2;
    sum += sqrt(p*(p-a)*(p-b)*(p-c));
    sum += c*c/4;
    return sum;
}
int main()
{
    double mid1,mid2,start,end,sq1,sq2;
    while(scanf("%lf%lf",&a,&b)!=EOF)
    {
        start = 0;
        end = a+b;
        while(start+eps < end)
        {
            mid1 = (start+end)/2;
            mid2 = (mid1+end)/2;
            sq1 = getsum(mid1);
            sq2 = getsum(mid2);
            if(sq1 > sq2-eps)
                end = mid2;
            else
                start = mid1;
        }
        printf("%.9lf\n",getsum(start));
    }
    return 0;
}