# Lock code game puzzle

I'm trying to solve a lock 3 code game, Can You Crack The Code. From time to time I find myself presented with a puzzle that has 2 possible solutions, but the game only allows one correct answer. For example, in the puzzle shown below, the possibilities I narrowed down are:

8 1 0   or   8 0 9

and I can't figure out which one is correct.

How do I know which answer to give?

• Hello and welcome to PSE! I'd advise you to read the tour page. Further, puzzles taken from elsewhere must provide an attribution to the original source, or they risk being deleted. Feb 4 '18 at 5:58
• Possible duplicate of Crack the lock code only numbers are diffrerent, even text is the same.
– Oray
Feb 4 '18 at 9:58
• Thanks for the feedback, the puzzle is taken from a game play.google.com/store/apps/… and as Oray said i found the same post wich is the same game. ive been trying to make a javascript solver for this code because the game repeats the rules and only changes the numbers. but there are certain conbinations that i get 2 results possibles. Feb 4 '18 at 18:31
• from the answer provided by jonMark im stuck in the same problem. Feb 4 '18 at 18:37
• @SebastianCardenas You should edit the attribution into the puzzle post. If the game presents this puzzle as shown, with the guesses already pre-filled, and you're supposed to use them to solve the code, then you should explain that as well (it's not obvious from the post if those were game-supplied or player-supplied guesses). If pre-filled, this game is bad—it's not possible to determine, short of by guessing, which of the equally valid possibilities is intended.
– Rubio
Feb 4 '18 at 21:49

Clues 1 and 5 tell you 8 is in the answer. Clue 2 puts 8 first, and with clues 3 and 4, we know 0 is in the answer. Clue 5 says one of the others is 1 or 9, and you are right - there isn't enough information to decide between 809 and 810.

I've concluded that

- 810
- 809

Summarizing the 5 conidtions (the 5 boxes) where rows are the possible numbers. x means not a valid digit at the given place for sure.
X/Y means X of the Y cases. Light green: possible digit Light red: possible "not"

It reduces the the options for the first 3 conditions:

Based on the 419 condition we can go with:
1. ?1?
2. ??9

Let's see the ?1? branch: 9 is out then:

Gives two options:81? or ?18:

81? leads to 810 which works:

The ??9 branch: number 1 is out, then 8?9 then 809:

Also this method proves that no other solutions exists.
Yellow: the new changes
Gray: changes due to new changes
Blue: number and place identified
Red: conflict

• 839 conflicts with clue #2. 319 conflicts with clue #1.
– JS1
Dec 20 '19 at 23:41
• Yes, I've realized this as well. TY. Corrected. Dec 21 '19 at 10:42

• That ... doesn't exclude the other possibility at all. 810 also would have one number is correct and well placed.