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c# barcode generator library MAGIC METHODS, PROPERTIES, AND ITERATORS in Font
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Matrix 2D Barcode Generation In Java Using Barcode creation for Java Control to generate, create Matrix Barcode image in Java applications. www.OnBarcode.comQR Printer In None Using Barcode drawer for Software Control to generate, create QR image in Software applications. www.OnBarcode.comTo represent a possible solution (or part of it), you can simply use a tuple (or a list, for that matter). Each element of the tuple indicates the position (that is, column) of the queen of the corresponding row. So if state[0] == 3, you know that the queen in row one is positioned in column four (we are counting from zero, remember ). When working at one level of recursion (one specific row), you know only which positions the queens above have, so you may have a state tuple whose length is less than eight (or whatever the number of queens is). Note I could well have used a list instead of a tuple to represent the state. It s mostly a matter of taste in this case. In general, if the sequence is small and static, tuples may be a good choice.
Finding Conflicts
Let s start by doing some simple abstraction. To find a configuration in which there are no conflicts (where no queen may capture another), you first must define what a conflict is. And why not define it as a function while you re at it The conflict function is given the positions of the queens so far (in the form of a state tuple) and determines if a position for the next queen generates any new conflicts: def conflict(state, nextX): nextY = len(state) for i in range(nextY): if abs(state[i]nextX) in (0, nextYi): return True return False The nextX parameter is the suggested horizontal position (x coordinate, or column) of the next queen, and nextY is the vertical position (y coordinate, or row) of the next queen. This function does a simple check for each of the previous queens. If the next queen has the same x coordinate, or is on the same diagonal as (nextX, nextY), a conflict has occurred, and True is returned. If no such conflicts arise, False is returned. The tricky part is the following expression: abs(state[i]nextX) in (0, nextYi)

