1045 - Digits of Factorial（数论）

题意：给定n、k，求出n的阶乘转化为k进制一共有几位。

思路：log(a*b)=log(a)+log(b)..............

题目链接：http://www.lightoj.com/volume_showproblem.php?problem=1045

View Code

 1 #include <cstdio>
 2 #include <cstring>
 3 #include <cmath>
 4 #include <string>
 5 #include <algorithm>
 6 #include <iostream>
 7 using namespace std;
 8 const int N=1000010;
 9 
10 double sum[N]={0,0};
11 
12 int main(){
13     
14 //    freopen("data.in","r",stdin);
15 //    freopen("data.out","w",stdout);
16     
17     int t,i,j,n,k;
18     scanf("%d",&t);
19     for(i=2;i<N;i++)
20         sum[i]=sum[i-1]+log10(i);    // log(a*b)=log(a)+log(b)
21     for(i=1;i<=t;i++){
22         scanf("%d%d",&n,&k);
23         int ans=sum[n]/(log10(k*1.0))+1;
24         printf("Case %d: %d\n",i,ans);
25     }
26     return 0;
27 }

posted @ 2012-05-14 11:10 Hug_Sea 阅读(162) 评论(0) 收藏举报

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