nqueens backtracing code example

Example: nqueens backtracing

def check(row, col):
	for prow in range(row):
		pcol = queens[prow]
		if(pcol == col or (abs(col - pcol) == abs(row - prow))):
			return False
	return True
def nqueens(row):
	global n, ans, queens
	if(row == n):
		ans+=1
		return
	else:
		for col in range(n):
			if(check(row, col)):
				queens.append(col)
				nqueens(row+1)
				queens.pop()


if __name__ == "__main__":
	n = input('Enter n: ')
	ans = 0
	queens = []
	nqueens(0)
	print(ans)