This puzzle is not very difficult but it is knowledge based.

In front of you there are 4 switches. From these switches there are 4 right combinations to open the gate to the control room. You can either turn on a switch(green) or turn it off(red).

However if you try any of the wrong switch combinations, the room security has hidden weapons set to kill you.

You found the document with the title "the key to controlling room".

"the document is the hidden note so only the person who created the gate key can understand the logic and can open the gate but somehow you get it after hacking into his system."

The document has only these letters inside it.

it doesn't matter whatever combination you try, I am the truth of OR

  • $\begingroup$ 4 right combinations. That means e.g. (XXXO) (XOOO) (XXXX) (XOXO) are accepted, but all other combinations lead to the security using their weapons. Correct? $\endgroup$
    – npkllr
    Commented Oct 17, 2019 at 11:43
  • $\begingroup$ @npkllr yes it could not be any random 4 combinations, the document is the hint. $\endgroup$ Commented Oct 17, 2019 at 11:44

2 Answers 2


Taking the idea of @Tonks partially correct answer:

An OR logic gate delivers the outputs 0,1,1,1 depending on the input.

Taking the hint "it doesn't matter whatever combination you try", the correct answer should be:

the four permutations of (XOOO), and therefore (XOOO)(OXOO)(OOXO)(OOOX).

  • 2
    $\begingroup$ Well done, I was thinking too rigidly about this one! $\endgroup$
    – Tonks
    Commented Oct 17, 2019 at 13:06

I think the truth of OR is...

...a programming logic gate; the 'truth' table for an OR logic gate is the following:
| A | B| A OR B |
| 0 | 0| 0 |
| 0 | 1| 1 |
| 1 | 0| 1 |
| 1 | 1| 1 |

Therefore, the answer is likely to be

XOOO assuming Xs are 0s and Os are 1s

  • 3
    $\begingroup$ There are 4 correct answers to find... $\endgroup$
    – JMP
    Commented Oct 17, 2019 at 12:21
  • $\begingroup$ Ah, I got ahead of myself here, I'll edit my answer $\endgroup$
    – Tonks
    Commented Oct 17, 2019 at 12:23
  • $\begingroup$ ROT13(sbhe pbeerpg nafjref + gur uvag "vg qbrfa'g znggre jungrire pbzovangvba lbh gel". Fb cbffvoyl gur pbeerpg pbzovangvbaf ner gur sbhe crezhgngvbaf bs (KBBB).) $\endgroup$
    – npkllr
    Commented Oct 17, 2019 at 12:31
  • $\begingroup$ @Tonks it is partially correct. $\endgroup$ Commented Oct 17, 2019 at 12:34

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