python解无忧公主的数学时间编程题001.py

"""

python解无忧公主的数学时间编程题001.py

http://mp.weixin.qq.com/s?__biz=MzI5ODEwMDQyNw==&mid=402273249&idx=4&sn=aa2e79e154a13c5c94673d9a53e49c96&scene=24&srcid=0323mNu08KMNzbVyn7EbUN1d#rd

2016年3月31日 05:16:39 codegay

0-9组成的字典序第一百万个是多少?

"""

from itertools import permutations

#方法1 使用enumerate()当作计数器,只取第一百万个数字.

result=[''.join([str(r) for r in v]) for k,v in enumerate(permutations(range(10)),1) if k==1000000]

print(result)

#['2783915460']

#[Finished in 0.6s]

#方法2 穷举后排序,取出一百万个数字.

result=[''.join([str(r) for r in v]) for k,v in enumerate(permutations(range(10)),1)]

result.sort()

print(result[1000001])

#2783915640

#[Finished in 14.2s]