8 Queens' Problem (Solved by Python 3.6)

def conflict(state,nextX):

    nextY=len(state) #next row

    for i in range(nextY): #go through 0 to nextY-1 rows

        if abs(state[i]-nextX) in (0,nextY-i):

        return True

    return False



def queens(num,state): #output a sequence

    if len(state)==num-1: #last row

        for pos in range(num): #go throuth 0 to num-1 columns

            if not conflict(state,pos): #if not conflict

            yield (pos,) #generate a tuple(pos,)

    else:

        for pos in range(num): #go throuth 0 to num-1 columns

            if not conflict(state,pos): #if not conflict

                for result in queens(num,state+(pos,)): #go through next queens()'results

                    yield (pos,)+result #generate a (pos,)+a next queens()'result



def prettyprint(solution):

    def line(pos,length=len(solution)):

        return '. '*(pos)+'X '+'. '*(length-pos-1)

    for pos in solution:

        print(line(pos))



import random

prettyprint(random.choice(list(queens(8,()))))

Results ( A Example )：

Functions and Statements：
(1) def [function name] ( [parameters] ):
[return or no return]
[yield]
(2) len( [object] )
(3) print( [strings] )
(4) range( [num] )=[0,1,2,...,num-1]
(5) list( [sequence] )=[sequence]

Methods:
（1）Recursion
A Example:

def factorial(n):
    if n==1:
        return 1   # ending condition
    else:
        return n*factorial(n-1)  # recursive formula

Reference:
Beginning Python From Novice to Professional (2nd Edition)