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Problem 79: Determine online banking password based on successful attempts

September 11, 2010

I solved the 79th Euler problem with pen and paper, since the input data was rather small (50 attempts, with repetitions).

The ideia is to find the shortest possible secret passcode based on a log fie containing 50 successful login attempts. Furthermore, the characters are asked in order, which eases the process of finding the solution.

So, I started with the first one: 319. This means that the number 3 will appear before 1 and 9; the number 1 will appear after 3 and before 9; finally, the number 9 will appear after 3 and 1. Then I continued with all the numbers in the log file. At the end, I just run a quick walkthrough the log file again to be sure. I ended up with the right solution: the password is 73162890.

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