| Time Limit: 1000MS | Memory Limit: 30000K | |
| Total Submissions: 13516 | Accepted: 3484 |
Description
When a thin rod of length L is heated n degrees, it expands to a new length L‘=(1+n*C)*L, where C is the coefficient of heat expansion. Input
Output
Sample Input
1000 100 0.0001 15000 10 0.00006 10 0 0.001 -1 -1 -1
Sample Output
61.329 225.020 0.000
题目：可以这样理解，给你一根木杆，夹在某物体之间。现在木杆会受热膨胀，膨胀增长，在两端物体的挤压下就会变弯曲，如上图所示。
从一根直的木杆变到弯曲的木杆，两种状态下，木杆中间位置的高度差是多少？
解法全在上面的图片中！
代码：
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <ctype.h>
#include <math.h>
#include <iostream>
#include <string>
#include <stack>
#include <algorithm>
#define eps 1e-5
using namespace std;
int main()
{
// L‘=(1+n*C)*L
double L, n, c;
while(scanf("%lf %lf %lf", &L, &n, &c)!=EOF)
{
if(L<0 && n<0 && c<0) break;
double low=0.0;
double high=0.5*L;
double mid;
double s=(1.0+n*c)*L;
double R;
while(high-low>eps){
mid=(low+high)/2.0;
R = (4*mid*mid+L*L)/(8*mid);//化简成一次除法 减小精度误差
if(2*R*asin(L/(2*R)) < s)
low=mid;
else
high=mid;
}
printf("%.3lf\n",mid);
}
return 0;
}
poj 1905 Expanding Rods(木杆的膨胀)【数学计算+二分枚举】
原文：http://www.cnblogs.com/yspworld/p/4729159.html