第四次集训—— Factstone Benchmark

Problem B: Factstone Benchmark

Amtel has announced that it will release a 128-bit computer chip by 2010, a 256-bit computer by 2020, and so on, continuing its strategy of doubling the word-size every ten years. (Amtel released a 64-bit computer in 2000, a 32-bit computer in 1990, a 16-bit computer in 1980, an 8-bit computer in 1970, and a 4-bit computer, its first, in 1960.)

Amtel will use a new benchmark - the Factstone - to advertise the vastly improved capacity of its new chips. The Factstone rating is defined to be the largest integer n such that n! can be represented as an unsigned integer in a computer word.

Given a year 1960 ≤ y ≤ 2160, what will be the Factstone rating of Amtel's most recently released chip?

There are several test cases. For each test case, there is one line of input containing y. A line containing 0 follows the last test case. For each test case, output a line giving the Factstone rating.

Sample Input

196019810

Output for Sample Input

38

#include <stdio.h>#include <math.h>int main(){   int n,i,w,j;   double sum;   while(scanf("%d",&n)!=EOF)   {       w = 1;       sum = 0;       if(n >= 1960 && n <= 2160)       {           i = (n-1960)/10 + 2;           for(j = 1;j<=i;j++)               w = w * 2;               j = 2;           for(;sum <= w;++j)               sum += log(j)/log(2);            printf("%d\n",j-2);       }       else if(n == 0)        break;   }    return 0;}