To Break The Safe in 5 Minutes...

What was the challenge? 

Re listing all the clues...

1st Clue: Exactly one number is perfectly placed.
9 2 5

2nd clue: Everything is incorrect.
9 3 8

3rd clue: Two numbers are part of the code of the safe, but are wrongly placed.
4 9 6

4th clue: One number is part of the code of the safe, but is wrongly placed.
5 8 1

5th clue: One number is part of the code of the safe, but is wrongly placed.
1 2 6 

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From 2nd clue, it's clear that 9,3,8 are not part of the code.

Hence correct number suggested by 1st clue must be 2 or 5

Since 9 is not part of the code, the other 2 correct numbers that 3rd clue pointing must be 4 and 6.

If 6 is the part of code, then 1 & 2 are not as 5th clue is suggesting.

And since 2 isn't part of the code then 1st clue must be pointing 5 is correct digit placed in right position.

The 4th clue is also suggesting that 5 is the part of the code but not 1 or 8.

If 5 is correct at it's position as per first clue then 4 and 6 must be occupying other 2 places.

As per 3rd clue position of 4 is wrong, it must be at second place and hence 6 at first place.

Hence the code is 645!