ds 1.1 单身狗的进化

/***************Problem from :dsProblem describe :给定n, 求n的阶乘的位数 样例:   input   output     10      7     20      19data:2016.12.1****************/#include<iostream>#include<cstdlib>#include<cstdio>#include<algorithm>#include<cmath>#include<map>#include<stack>#include<queue>#include<ctime>#include<cstring>#include<vector>#include<string>#define ll __int64#define inf 0x3f3f3f3f3fusing namespace std;int main(){//  freopen("in.txt","r",stdin);//  freopen("out.txt","w",stdout);//  n! ≈10 ^ m   求m   //  可转化成  m = lg(n!) = lg1 + lg2 + ... +lgn;//  调用math库中的 log    int i, n;    //至少是一位数  而且 lg1 lg2 lg3 <1;    while(~scanf("%d", &n))    {        double ans=1;        for(i=1; i<=n; i++) ans+=log10(i);        printf("%d\n", (int)ans);        }    return 0;}