UVA - 10916 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. TheFactstone rating is defined to be the largest integer n such thatn! 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 containingy. 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<math.h>#include<iostream>#include<stdio.h>#include<string.h>using namespace std;int main(){int n;while(scanf("%d",&n)){if(n == 0)break;double sum = 0;int m = 4 << (n - 1960) / 10;int i;for( i = 1;;){sum += log(i) / log (2.0);if(sum > m)break;i++;}printf("%d\n",i - 1);}return 0 ;}