codesamples/Python/capstone.pyw

from graphics import *
import time

'''This program accepts a number n from the user, generates an nxn board,
allows the user to place n queens, and checks to see if any of the queens
can attack each other under the standard rules of chess: in other words,
it determines if there is more than one queen in any given row, column, or
diagonal. It then highlights any queens that are placed incorrectly. It uses a
completely graphical interface - the command line need not be used.'''

def smallcrown(point, win):
    '''draws a crown shape to represent a queen within a specified square
    on a board'''
    x = int(point.getX())
    y = int(point.getY())
    poly = Polygon(Point(x+.7, y+.3), Point(x+.3, y+.3), Point(x+.2, y+.6), Point(x+.35, y+.45), Point(x+.43, y+.6), Point(x+.5, y+.47), Point(x+.58, y+.6), Point(x+.65, y+.45), Point(x+.8, y+.6))
    poly.draw(win)

def drawboard(win, n):
    '''draws a square grid of a specified size'''
    for i in range(n):
        line = Line(Point(i,0), Point(i, n))
        line.setWidth(1)
        line.draw(win)
    for i in range(n):
        line = Line(Point(0,i), Point(n,i))
        line.setWidth(1)
        line.draw(win)

def placequeen(win, n):
    '''allows the user to place a specified number of 'queens' on a square
    board'''
    drawboard(win, n)
    pointX = []
    pointY = []
    for i in range(n):
        point = win.getMouse()
        pointX.append(int(point.getX()))
        pointY.append(int(point.getY()))
        smallcrown(point, win)
    return pointX, pointY

def getMatrix(win, n):
    '''converts a board with n placed queens into a list of rows,
    with an empty space represented by 0 and a queen represented by 1'''
    X, Y = placequeen(win, n)
    Xrows = [[]]*n
    Yrows = [[]]*n
    for i in range(n):
        Xrows[i] = [0]*n
        Yrows[i] = [0]*n
    for i in range(n):
        Xrows[Y[i]][X[i]] = 1
        Yrows[X[i]][Y[i]] = 1
    return Xrows, Yrows

def coord(n, x, y, qn):
    '''Takes row descriptions created by getMatrix and returns the following
    information for each queen: x, y, x+y, x-y'''
    coords = [[0,0]]*n
    coord = 0
    for row in range(n):
        for col in range(n):
            if x[row][col] == qn:
                coords[coord] = [row,col,row+col,row-col]
                coord += 1
    return coords

def checkbit(n, coords, bp):
    '''uses a subset of the information generated by coord and uses it to
    check if there are multiple queens in any row, column, or diagonal. Makes
    a list of the (x,y) coordinates of those queens'''
    dct = {}
    lst = []
    for i in range(n):
        k = coords[i][bp]
        if dct.has_key(k):
            dct[k] = dct[k] + coords[i][0:2]
        else:
            dct[k] = coords[i][0:2]
    lst = dct.values()
    queens = []
    if len(lst) < n:
        for i in range(len(lst)):
            if len(lst[i]) <> 2:
                for b in range(0, len(lst[i]), 2):
                    queens = queens + [lst[i][b:b+2]]
    return queens

def checker(n, x, y, qn):
    '''Calls checkbit for each type of coordinate in turn'''
    coords = coord(n, x, y, qn)
    rows = checkbit(n, coords, 0)
    cols = checkbit(n, coords, 1)
    diag1 = checkbit(n, coords, 2)
    diag2 = checkbit(n, coords, 3)
    return rows, cols, diag1, diag2


def main():
    '''This is the function to invoke to run the entire program'''
    win = GraphWin("Some Queens", 500, 500)
    f = Text(Point(250, 220), "Please enter a number for size of board")
    f.draw(win)
    e = Entry(Point(250, 250), 4)
    e.draw(win)
    b = Text(Point(250, 280), "Click to continue")
    b.draw(win)
    win.getMouse()
    n = int(e.getText())
    e.undraw()
    f.undraw()
    b.undraw()
    win.setCoords(0,0,n,n)
    x, y = getMatrix(win, n)
    rows, cols, diag1, diag2 = checker(n, x, y, 1)
    queens = rows + cols + diag1 + diag2
    time.sleep(0.5)
    if len(queens) == 0:
        t = Text(Point(n/2.0, (3*n)/4.0), "You're right!")
        t.setFill('blue')
        t.setSize(36)
        t.setStyle('bold')
        t.draw(win)
    else:
        for i in range(len(queens)):
            x = queens[i][0]
            y = queens[i][1]
            sqr = Rectangle(Point(y, x), Point(y+1, x+1))
            sqr.setFill('red')
            sqr.draw(win)
            smallcrown(Point(y, x), win)
        t = Text(Point(n/2.0, (3*n)/4.0), "Sorry, try again :(")
        t.setFill('blue')
        t.setSize(36)
        t.setStyle('bold')
        t.draw(win)
    clo = Text(Point(n/2.0, n/2.0), "Click to close")
    clo.setFill('blue')
    clo.setSize(20)
    clo.draw(win)
    win.getMouse()
    win.close()
    return

main()