Four coins are placed in a row: Heads, Tails, Heads, Tails. In one move, you must flip any two adjacent coins. What is the minimum number of moves required to make all four coins show Heads?
2 moves
Initial state: H T H T. Move 1: Flip the middle two coins (indices 2 and 3, which are T and H), turning them into H and T respectively? No, flip adjacent coins 2 and 3 (T and H) -> H H H T. Move 2: Flip the last two coins (H and T) -> H H H H. Total moves: 2.
About this riddle
Logic riddles give you a few facts and ask what must be true. List what you know, cross out what cannot be, and see what is left.
Difficulty: Medium. More like this: Logic riddles with answers or try Einstein's Logic Grid for a different kind of puzzle.
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