FZU 1148 Crossed ladders

Accept: 126    Submit: 251
Time Limit: 1000 mSec    Memory Limit : 32768 KB

 Problem Description

A narrow street is lined with tall buildings. An x foot long ladder is rested at the base of the building on the right side of the street and leans on the building on the left side. A y foot long ladder is rested at the base of the building on the left side of the street and leans on the building on the right side. The point where the two ladders cross is exactly c feet from the ground. How wide is the street?

 

 

 Input

Each line of input contains three positive floating point numbers giving the values of x, y, and c.

 Output

For each line of input, output one line with a floating point number giving the width of the street in feet, with three decimal digits in the fraction.

 Sample Input

30 40 10 12.619429 8.163332 3 10 10 3 10 10 1

 Sample Output

26.033 7.000 8.000 9.798

//二分逼近

#include<iostream>#include<cmath>#define N 0.000000001//c= sqrt((y*y-w*w)*(x*x-w*w))/(sqrt(y*y-w*w) + sqrt(x*x -w*w)) int main(){double x,y,c,sum,i,j,p;while(scanf("%lf%lf%lf",&x,&y,&c)!=EOF){i=0;p=0;if(c==0){printf("%.3lf/n",x);continue;}if(x<y) j=x;else j=y;while(1){p=(i+j)/2;sum=1.0/(sqrt(x*x-p*p))+1.0/sqrt(y*y-p*p);sum=1.0/sum;if(fabs(c-sum)<N)break;if(sum<c)j=p-N;elsei=p+N;}printf("%.3lf/n",p);}return 0;}