2990819_ac_0ms_116k.c

北大大牛代码 1240道题的原代码 超级权威

#include <stdio.h>

int main()
{
	int n, k;
	double p, w, t;

	while(scanf("%d%lf",&n,&p)==2,n)
	{
		w = 1<<n;
		for(k = n-1; k >= 0; k--)
		{
			t = (1<<k)/w;
			if(p >= t)
				w = (p+1)/2*w;
			else
				w = (1<<k)*(t-p)/(1-p)+w*(t+1)/2*(1-t)/(1-p);
		}
		printf("%.3lf\n",w);
	}
	return 0;
}