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Chess - Programming - de Bruijn Sequence - About De Bruijn Sequences

Imagine a 4-digit PIN number.

this means there can be 10,000 unique four-digit combinations, from 0000 to 9999.
this also means 40,000 key presses.

Is there a quick way of going through all combinations without that number of key presses? Yes.

NOTE: Simply look at just the last four keys pressed.

Attempt 1: 1234 is entered.
Attempt 2: Only a 7 is entered. The system sees the last four digits as 2347.
Attempt 3: Only a 9 is entered. The system sees the last four digits as 3479.

So for Attempts 2 and 3, instead of 4 digits needing to be entered, only a single digits has been needed.

References