The Eight Queens Puzzle

The "eight queens" puzzle is a well-known puzzle, going back to 1848. The problem is to try to place eight queens on a chessboard so that none of them are attacking any of the others - remember that the queen can move as far as she likes vertically, horizontally or diagonally. You can't place two queens in the same row, for example, so on a normal chessboard (8 by 8), you can't put nine or more queens. Eight is the maximum.

The puzzle below shows an empty 4 by 4 chessboard, all in gray. The 4 by 4 board is easier than the 8 by 8, so it's a good size to start with. Click on a square to place a queen, and the square will turn green. The squares that the queen is attacking will turn blue. See if you can place four queens on the 4 by 4 board! To remove a queen, click on it again.

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Jon D Jones

Software Architect, Programmer and Technologist Jon Jones is founder and CEO of London-based tech firm Digital Prompt. He has been working in the field for nearly a decade, specializing in new technologies and technical solution research in the web business. A passionate blogger by heart , speaker & consultant from England.. always on the hunt for the next challenge

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