Exploiting patterns is an important part of breaking codes. It turns out that humans are poor at randomness, and often exhibit subtle breaks from randomness that can be exploited. One such example would be generating a set of random letters or a random password. A truly random password could include any character and may include repeats of characters. A human would feel that this is somehow not random enough and so might choose a key from the left side of the keyboard, followed by one on the right, and so on$.$ This leads to an exploitable pattern. We will explore such patterns in actual words by using trees.

In this case, we will read two sets of letters from a file and use them to parse a large number of words from the yawl.txt file using the sets of letters. This file contains a large number of words that are generally accepted for word puzzles. We will then find words that match a number of requested letter patterns.