POJ1905 Expanding Rods（二分）

题意：

给一个长度为L的钢条，加热后长度改变并且弯曲成一个弧，算出之间的距离

要点：

基础思想是二分，但其实里面包含了很多证明

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15301383

Seasonal

1905

Accepted

196K

0MS

C++

510B

2016-03-22 20:56:20

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<math.h>
double l, n, c,L;
double r;

double depart(double left, double right)
{
	double h, r, ll;
	while (right-left>0.000001)//精确度6位
	{
		h = (left + right) / 2.0;
		r = (4 * h*h + l*l) / (8 * h);
		ll = 2 * r*asin(l / (2 * r));
		if (ll > L)
			right = h;
		else
			left = h;
	}
	return h;
}

int main()
{
	while (~scanf("%lf%lf%lf", &l, &n, &c))
	{
		if (l == -1)
			break;
		L = l*(1 + n*c);
		printf("%.3lf\n", depart(0, l / 2.0));
	}
	return 0;
}

转载于:https://www.cnblogs.com/seasonal/p/10343816.html