Hi, all

I seemed to have problem understanding what "30 Substring with Concatenation of All Words" asks for.

This is problem definition:
You are 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.
For example, given:
s: "barfoothefoobarman"
words: ["foo", "bar"],
you should return the indices: [0,9].(order does not matter).

From what I understand, I think the answer for input:
s : "barfoofoobarthefoobarman"
words : ["bar","foo","the"]
should be [0,6,15] since 0 for "barfoo", 6 for "foobarthe", 15 for "foobar"

However expected answer is:[6,9,12]. Could someone kindly help answer how come the expected answer is [6,9,12]?

Thanks in advance!
Li