用Python做50道ACM之《Number lengths》

22.Number lengths

http://acm.fzu.edu.cn/problem.php?pid=1050

import sys
import math

def factorial_len(n):
    result=0
    for i in range(1,n+1):
        result+=math.log10(i)
    return int(result+1)

for each in sys.stdin:
    n=int(each.rstrip())
    print(factorial_len(n))