> For the complete documentation index, see [llms.txt](https://851958789.gitbook.io/notes/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://851958789.gitbook.io/notes/0030_substring_with_concatenation_of_all_words/slt.md).

# 思路1

双重循环遍历s和words，用两个hash，一个记录words中的word count，另一记录s中出现了的word count。

时间复杂度`O(s.size() * words.size())`