Sunday July 24, 2011
This problem involves cracking a login passcode using simple patterns.
A common security method used for online banking is to ask the user for three random characters from a passcode. For example, if the passcode was 531278, they may ask for the 2nd, 3rd, and 5th characters; the expected reply would be: 317.

The text file below, log.txt, contains fifty successful login attempts.

Given that the three characters are always asked for in order, analyze the file to determine the shortest possible secret passcode of unknown length.

(This problem and its text come from Project Euler).
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