题目
Given a non-empty string check if it can be constructed by taking a substring of it and appending multiple copies of the substring together. You may assume the given string consists of lowercase English letters only and its length will not exceed 10000.
解题思路
如果该字符串符合条件，那么将其重复两次，并去掉两端的字符串，一定包含该字符串
设t = s + s，若s在t中的起始位置不为0或n，则符合条件，那么设这个起始位置为i (0<i<n),s[x:y]表示s的第x个字符到第y个字符
s[0: n - 1] = t[i: n + i - 1]
将t[i: n + i - 1]在n - 1位置分成两段
s[0: n - i - 1] = t[i: n - 1]
s[n - i: n - 1] = t[n: n + i - 1] = t[0: i - 1]
s[0: n - i - 1] = s[i: n - 1]
s[n - i: n - 1] = s[0: i - 1]
对于任意j，s[j % n] = s[(j + i) % n]
代码
class Solution:
def repeatedSubstringPattern(self, s: str) -> bool:
return (s + s).find(s, 1) != len(s)
