Puzzle Library

Two stairways lead to Heaven or Hell. Three guards stand before them: an Angel (truthful), a Devil (lies), and a Human (unpredictable). You don't know who is who. You can ask two yes/no questions total (to any guards). Each guard knows the others' identities. How do you find Heaven's stairway?

5 boxes in a row contain a cat that moves to an adjacent box each night. Each morning, you check one box. What sequence of checks guarantees finding the cat within 6 days, regardless of starting position or movement pattern?

Three people sit in a circle, each wearing a red, blue, or white hat. Each sees the other two hats but not their own. They agree on a strategy beforehand, then simultaneously guess their hat color. At least one must be correct. What strategy works?

Two people sit facing each other, each wearing either a red or blue hat. They can see the other's hat but not their own. Before hats are placed, they agree on a strategy. Then they must simultaneously guess their hat color. Goal: at least one must be correct. What strategy guarantees success?

You're at a fork with two paths: one to Heaven, one to Hell. Two guards stand there - an Angel (always truthful) and a Demon (always lies), but you don't know who is who. You can ask ONE yes/no question to ONE guard. What question guarantees you find the path to Heaven?

Three friends A, B, and C play table tennis with these rules: winner stays to play the next match, loser is replaced by the person who rested. After all matches: A played 10 games, B played 15 games, C played 17 games. Who lost the second match?

Seven colleagues are discussing what day today is. Each makes one statement: A: 'The day after tomorrow is Wednesday.' B: 'No, today is Friday.' C: 'That's wrong, tomorrow is Wednesday.' D: 'Today is neither Monday, nor Wednesday, nor Friday.' E: 'Yesterday was Thursday.' F: 'Tomorrow is Thursday.' G: 'Yesterday wasn't Saturday.' Only ONE person is telling the truth. What day is it?

In a national sales competition, each company sends exactly 3 employees. Company X sends A, B, and C. Results: A ranks exactly in the middle of all participants. B ranks 19th (lower than A). C ranks 28th. How many companies participated?

In front of you stand three villagers: One is an Angel (always tells the truth), one is a Demon (always lies), and one is a Human (sometimes tells the truth, sometimes lies). Each makes one statement: A says: 'I am not the Angel.' B says: 'I am not the Demon.' C says: 'I am not a Human.' What are the true identities of A, B, and C?

Someone has embezzled money from the company. Employee A says: 'The culprit is B!' Employees B and C also made statements, but we don't know what they said. We know that: The culprit is one of A, B, or C, and only the culprit is telling the truth; the other two are lying. Who is the real culprit?

There are three boxes: one contains only apples, one contains only oranges, and one contains both apples and oranges. Each box is labeled, but ALL labels are wrong. You can pick one fruit from one box. How can you correctly label all three boxes?