Place N chess queens on an N×N chess board so that no two queens attack each other

N Queens.py

#!/usr/bin/env python3

def n_queens(array, n, row):
	if row >= n:
		for i in range(n):
			for j in range(n):
				if array[i][j] == 1:
					print("x", end = ' ')
				else:
					print("o", end = ' ')
			print()

		for i in range(n):
			for j in range(n):
				if array[i][j] == 1:
					print(f"({i},{j}) ", end = ' ')
		print("\n")

		return 1

	k = 0

	for i in range(n):
		if is_safe(array, row, i, n):
			array[row][i] = 1
			k += n_queens(array, n, row+1)
			array[row][i] = 0

	return k


def is_safe(array, x, y, n):
	if x == 0:
		return True

	flag = True
	
	for z in range(x, 0, -1):
		if x-z >= 0 and y-z >= 0 and array[x-z][y-z] != 0:
			flag = False
			break
		if x-z >= 0 and array[x-z][y] != 0:
			flag = False
			break
		if x-z >=0 and y+z < n and array[x-z][y+z] != 0:
			flag = False
			break
	
	return flag


if __name__ == '__main__':
	n = 8
	board = [[0 for i in range(n)] for j in range(n)]

	count = n_queens(board, n, 0)

	print(count)