Substring with Concatenation of All Words

For given a string, s, and a list of words, words, that are all of the same length. Find all starting indices of substring(s) in s that is a concatenation of each word in words exactly once and without any intervening characters.

Latest Source Code:
Github: ConcatenationSubstring.java

Output:

String : barfoothefoobarman, Words: [foo, bar], Indices: [0, 9]
String : wordgoodgoodgoodbestword, Words: [word, good, best, good], Indices: [8]