CSC111 drawChessBoard.py

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# chess.py
# D. Thiebaut
# Draws a board with 8 queens on it, in such a way
# that none of them can take each other.
# The text exquivalent is shown below.
"""
Q . . . . . . .
. . . . Q . . .
. . . . . . . Q
. . . . . Q . .
. . Q . . . . .
. . . . . . Q .
. Q . . . . . .
. . . Q . . . .
"""

from graphics import *

def drawBoard( win, N, side, border ):
    """draw the board, including border and black and white
    squares.  N is the number of squares on the side.  side 
    is the width of a square.  border is the gutter around the
    squares"""
    #--- draw the border first ---
    r = Rectangle( Point( border, border ),
                   Point( border+N*side, border+N*side ) )
    r.draw( win )

    #--- then all the black squares only ---
    for row in range( N ):
        drawRow( win, N, side, border, row )

def drawRow( win, N, side, border, row ):
    """draws one row of black squares on the board.  if row is 0
    the first top row is drawn."""

    #--- offset every even row by 1 square width ---
    offset = (row % 2) * side

    #--- place half of N black squares ---
    for c in range( 0, N, 2 ):
        x = border + offset + c * side
        y = border + row * side  # must use row somehow
        x2 = x + side
        y2 = y + side
        r = Rectangle( Point( x, y ), Point( x2, y2 ) )
        r.setFill( "black" )
        r.draw( win )

def drawSolution( win, N, side, border, solution ):
    """Given a solution for N queens on the board, show them as
    red circles"""
    for row, col in solution:
        centerX = border + col*side + side/2
        centerY = border + row*side + side/2
        queen = Circle( Point( centerX, centerY ), side/4 )
        queen.setFill( "red" )
        queen.draw( win )
        
def main():
    #--- the controlling parameters ---
    N        = 8           # number of squares on a side 
    border   = 20       # gutter around the board
    side     = (200-2*border) / N      # size of a square
    solution = [ [0,0],[1,4],[2,7],[3,5],[4,2],[5,6],[6,1],[7,3] ]
    
    #--- open a window ---
    win = GraphWin( "Chessboard" )

    #--- draw the board, then the queens ---
    drawBoard( win, N, side, border )
    drawSolution( win, N, side, border, solution )

    #--- wait for users to click mouse on window ---
    win.getMouse(  )
    win.close()

main()

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