In an obscure land, Barry has been convicted and sentenced to death. However, he has been given one last chance to save himself. There are three doors that lead out of the courtroom (not counting the door by which he came in, which can be opened only from the outside). One is the exit from the complex to freedom, one leads to the execution room and another leads to a dungeon where he will be imprisoned for the rest of his life should he go there. In front of each door is a guard. Before choosing a door, Barry is allowed to ask each guard a question. However, there is a catch. All three guards know which door leads where, but the guard of the door to freedom always tells the truth, the guard of the door to the execution room always lies, and the guard of the door to the dungeon may either lie or tell the truth.
First, Barry asks the guard of the door on the left, “Where does the door on the right lead?” The guard answers: “It leads out of the complex.” The guard in the middle is next in line, and is asked the same question. His answer: “It leads to the execution room.” The guard of the right-hand door is again asked, “Where does this door lead?” “It leads into the dungeon,” says this guard.
Which door must Barry choose in order to liberate himself? Once a door is opened, there’s no turning back!
Could the guards have answered in any other way, staying within their truth/lie policies, such that Barry could have still been certain of choosing the correct door?
Fill the grid with the numbers from 1 to 9, such that each number appears exactly once in each row, each column and each of the nine 3×3 blocks.
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