PAT 1023 Have Fun with Numbers-优快云博客

本文链接：https://blog.youkuaiyun.com/qaqlalala/article/details/113920452

该博客探讨了一个数学问题，即检查一个正整数翻倍后，其数字是否仍为原数字的不同排列。通过使用Python的collections.Counter来统计每个数字的出现次数，判断翻倍前后的数字计数是否一致，从而确定是否满足题目条件。示例输入为1234567899，输出为Yes，表明翻倍后的数字2469135798是原数字的一个不同排列。

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问题描述

Notice that the number 123456789 is a 9-digit number consisting exactly the numbers from 1 to 9, with no duplication. Double it we will obtain 246913578, which happens to be another 9-digit number consisting exactly the numbers from 1 to 9, only in a different permutation. Check to see the result if we double it again!

Now you are suppose to check if there are more numbers with this property. That is, double a given number with k digits, you are to tell if the resulting number consists of only a permutation of the digits in the original number.

Input Specification:
Each input contains one test case. Each case contains one positive integer with no more than 20 digits.

Output Specification:
For each test case, first print in a line “Yes” if doubling the input number gives a number that consists of only a permutation of the digits in the original number, or “No” if not. Then in the next line, print the doubled number.

Sample Input:
1234567899
Sample Output:
Yes
2469135798

思路分析及代码实现

这道题就时统计两个数中各个数字出现的次数，如果相等就是对的，可以借用collections中的Counter方法

import collections
n = int(input())
m = n * 2
_n = collections.Counter(list(str(n)))
_m = collections.Counter(list(str(m)))
if _n == _m:
    print('Yes')
else:
    print('No')
print(m)