Merged String Checker 5kyu

问题描述：

At a job interview, you are challenged to write an algorithm to check if a given string, s, can be formed from two other strings, part1 and part2.

The restriction is that the characters in part1 and part2 should be in the same order as in s.

The interviewer gives you the following example and tells you to figure out the rest from the given test cases.

For example:

'codewars' is a merge from 'cdw' and 'oears':

    s:  c o d e w a r s   = codewars
part1:  c   d   w         = cdw
part2:    o   e   a r s   = oears

根据问题描述，主要是判断part1+part2 是否可以组成 S，字符串不能重复出现。

我的解题思路：

可以把part1和part2合并，与s去比较字符出现次数，如果都是2那就是一致。

上代码：

def is_merge(s, part1, part2):
    text=s+''.join(part1)+''.join(part2)
    for i in text:
        num=text.count(i)
        if num==1:
            return False
    return True