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Substring with Concatenation of All Words

Explore how to identify all starting indices of substrings that form concatenations of all words provided. This lesson teaches you to apply the sliding window method to solve the problem efficiently, understand problem constraints, and implement a solution that handles permutations of word concatenations without intervening characters.

Statement

You are given a string, s, and an array of strings, words. All strings in words are of the same length.

A concatenated string is a string that contains all the words in words exactly once, in any order, concatenated together without any intervening characters.

Formally, a concatenated string is a permutation of all words joined together. For example, if words = ["ab", "cd", "ef"], then the following are all valid concatenated strings: "abcdef", "abefcd", "cdabef", "cdefab", "efabcd", "efcdab". However, "acdbef" is not valid because it is not formed by concatenating all the words in any order.

Your task is to return all starting indices of substrings in s that are concatenated strings.

You may return the indices in any order.

Constraints:

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