Jumbled Letters
You may have seen the following meme text on Internet (click the text if you want to read its "normal" version):
Aoccdrnig to a rsceearh at Cmabrigde Uinervtisy, it deosn't mttaer in waht oredr the ltteers in a wrod are, the olny iprmoetnt tihng is taht the frist and lsat ltteer be at the rghit pclae. The rset can be a toatl mses and you can sitll raed it wouthit porbelm. Tihs is bcuseae the huamn mnid deos not raed ervey lteter by istlef, but the wrod as a wlohe.
According to a research at Cambridge University, it doesn't matter in what order the letters in a word are, the only important thing is that the first and last letter be at the right place. The rest can be a total mess and you can still read it without problem. This is because the human mind does not read every letter by itself but the word as a whole.
Well, there are elements of truth in this. Here is a very interesting article from the real Cambridge University researcher, who is breaking down the meme and explain the phenomena.
Let's try to evaluate a level of jumbling. In this mission you are given two words - normal and jumbled version. If the jumbled one is not a version of a normal or rule is not followed, you function must return -1. For the totally same looking words return 0, of course. Otherwise, exclude first and last characters (they are not jumbled according to the rule) and return an average distance (rounded to 2 digits) between normal position of a character and its jumbled position.
If there are two or more same letters in a word, consider that the first appearance of a character in a normal version is equivalent to the first appearance of that character in a jumbled version etc.
Look at the example.
Input: Two strings (str).
Output: Float number (float).
Examples:
assert jumbled("vehicle", "vheclie") == 1.2
assert jumbled("checkpoint", "cehkipont") == -1
assert jumbled("doctor", "doctor") == 0
assert jumbled("research", "rsceearh") == 1.67
