# POJ 1905 Expanding Rods (二分+计算几何+精度处理)

```#include <iostream>
#include <string.h>
#include <math.h>
#include <queue>
#include <algorithm>
#include <stdlib.h>
#include <map>
#include <set>
#include <stdio.h>
using namespace std;
#define LL __int64
#define pi acos(-1.0)
const int mod=9901;
const int INF=0x3f3f3f3f;
const double eqs=1e-6;
bool Judge(double f1, double f2)
{
return f2-f1>1e-4;
}
bool judge(double f1, double f2)
{
return fabs(f1-f2)<eqs;
}
double bin_search(double lenth, double L)
{
double low=0, high=L/2, mid, r;
while(Judge(low,high)){
mid=(low+high)/2;
r=(4*mid*mid+L*L)/(8*mid);
if(2*r*asin(L/(2*r)) < lenth)
low=mid;
else high=mid;
}
return mid;
}
int main()
{
double L, c, n, lenth;
while(scanf("%lf%lf%lf",&L,&c,&n)!=EOF&&L>=0){
lenth=(1+n*c)*L;
printf("%.3f\n",bin_search(lenth, L));
}
return 0;
}
```

POJ 1905 Expanding Rods (二分+计算几何+精度处理)

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Description When a thin rod of length L is heated n degrees, it expands to a new length L'=(1
Expanding Rods Time Limit: 1000MS Memory Limit: 30000K Total Submissions: 10187 Accepted: 259

Link：http://poj.org/problem?id=1905 Expanding Rods Time Limit: 1000MS Memory Limit: 30000K T

Expanding Rods Time Limit:1000MS Memory Limit:30000KB 64bit IO Format:%I64d & %I64u Submit St