N-Queens
Place n queens on an n×n chessboard such that no two queens attack each other Return all distinct solutions as board configurations 'Q' = queen, '.' = empty space Example: n = 4 => [[".Q..","...Q","Q...","..Q."],["..Q.","Q...","...Q",".Q.."]]
N-Queens is about exploring choices without getting lost—choose, recurse, undo, repeat. It's a hard one for a reason: it stresses structured exploration when the rules pile up. The gotcha is duplicates and dead ends—good pruning and ordering rules make this manageable.
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