rooks.py

class board:
    def __init__(self,size):
        self.s=size
        self.b=[0 for x in xrange(size*size)]

    def get(self,x,y):
        return self.b[x+self.s*y]

    def set(self,x,y,v):
        self.b[x+self.s*y]=v

    def pr(self):
        for x in xrange(self.s):
            for y in xrange(self.s):
                print self.get(x,y),
            print ''
        print ''

    def copy(self):
        b=board(self.s)
        for x in xrange(self.s):
            for y in xrange(self.s):
                b.set(x,y,self.get(x,y))
        return b
    
    def verify(self):
        for x in xrange(self.s):
            fx=False
            fy=False
            for y in xrange(self.s):
                if fx:
                    if self.get(x,y) == 'r':
                        return False
                else:
                    if self.get(x,y) == 'r':
                        fx=True
                if fy:
                    if self.get(y,x) == 'r':
                        return False
                else:
                    if self.get(y,x) == 'r':
                        fy=True
        return True

def solns(b,x):
    for y in xrange(b.s):
        c=b.copy()
        c.set(x,y,'r')
        if x == c.s-1:
            if c.verify():
                yield c
        else:
            if c.verify():
                for s in solns(c,x+1):
                    yield s

from sys import argv
b = board(int(argv[1]))
soln = [s for s in solns(b,0)]
for sol in soln:
    sol.pr()