You are given a string s and an array of strings words. All the strings of words are of the same length.
A concatenated string is a string that exactly contains all the strings of any permutation of words concatenated.
Return an array of the starting indices of all the concatenated substrings in s. You can return the answer in any order.
Example 1:
Input: s = "barfoothefoobarman", words = ["foo","bar"]
Output: [0,9]
Explanation: The substring starting at index 0 is "barfoo", which is a concatenation of ["bar","foo"]. The substring starting at index 9 is "foobar", which is a concatenation of ["foo","bar"].
Example 2:
Input: s = "wordgoodgoodgoodbestword", words = ["word","good","best","word"]
Output: []
Explanation: No substring of the required length is a valid concatenation of all words.
Example 3:
Input: s = "barfoofoobarthefoobarman", words = ["bar","foo","the"]
Output: [6,9,12]
Explanation: The substring starting at index 6 is "foobarthe", at 9 is "barthefoo", and at 12 is "thefoobar".
1 <= s.length <= 10^41 <= words.length <= 50001 <= words[i].length <= 30s and words[i] consist of lowercase English letters.