nqueens.py

from math import *
import sys

x = {}
n = int(sys.argv[1])

def place(k, i):
    if (i in x.values()):
        return False
    j = 1
    while(j < k):
        if abs(x[j]-i) == abs(j-k):
            return False
        j+=1
    return True

def NQueens(k):
    for i in range(1, n + 1):
        if place(k, i):
            x[k] = i
            if (k==n):
                for j in x:
                    print x[j]
            else:
                NQueens(k+1)


NQueens(1)