> 是不是 有那个测试数据超时呢？帮忙分析一下
> #include<stdio.h>
> #include<math.h>
> 
> float f(float x,float y,float c,float L)
> {
> 	return (sqrt((y*y-L*L)*(x*x-L*L)))/(sqrt(x*x-L*L)+sqrt(y*y-L*L))-c;
> }
> 
> int main()
> {
> 	float x,y,c;
> 	float down,min,up,temp,L,temp1;
> 	while(EOF!=scanf("%f %f %f",&x,&y,&c)){
> 		down=0.0;
> 		if(x<y) up=x;
> 		else up=y;
> 		min=(down+up)/2;
> 		L=min;
> 		temp=f(x,y,c,L);
> 
> 		temp1=temp;
> 		if(temp1<0) temp1=-temp1;
> 		while(temp1>0.0001){
> 			if(temp<0) up=min;
> 
> 			if(temp>0) down=min;
> 			min=(down+up)/2;
> 			L=min;
> 			temp=f(x,y,c,L);
> 			
> 			temp1=temp;
> 		    if(temp1<0) temp1=-temp1;
> 		}
> 		printf("%.3f\n",L);
> 		
> 
> 	}
> 
> 	return 0;
> }
> /*
> 
> 30 40 10
> 12.619429 8.163332 3
> 10 10 3
> 10 10 1
> 
> */