hdu 1018 Big Number 数学结论 Big Number
Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 34084 Accepted Submission(s): 16111
Problem Description
In many applications very large integers numbers are required. Some of these applications are using keys for secure transmission of data, encryption, etc. In this problem you are given a number, you have to determine the number of digits in the factorial of the number.
Input
Input consists of several lines of integer numbers. The first line contains an integer n, which is the number of cases to be tested, followed by n lines, one integer 1 ≤ n ≤ 107 on each line.
Output
The output contains the number of digits in the factorial of the integers appearing in the input.
Sample Input
2
10
20
Sample Output
7
19
看到这个题就像用java写，结果超时。其实这是一道规律题：
N！的长度=log10（i）【i：2~n】+1;
然后就简单了。
#include<iostream> #include<stdio.h> #include<math.h> using namespace std; int main() { int t; scanf("%d",&t); while(t--) { int n; scanf("%d",&n); double tmp=0; for(int i=2;i<=n;i++) tmp+=log10(i+0.0); int ans =(int)tmp+1; printf("%d ",ans); } return 0; }