"""
	doctests

	>>> decimal_to_binary(3,[1.5])
	['0.00.01.5']

	>>> check(['0.00.01.5'])
	['0.00.01.5']

	>>> prime_implicant_chart(['0.00.01.5'],['0.00.01.5'])
	[[1]]

	>>> selection([[1]],['0.00.01.5'])
	['0.00.01.5']
"""
def compare_string(string1, string2):
	l1 = list(string1); l2 = list(string2)
	count = 0
	for i in range(len(l1)):
		if l1[i] != l2[i]:
			count += 1
			l1[i] = '_'
	if count > 1:
		return -1
	else:
		return("".join(l1))

def check(binary):
	pi = []
	while 1:
		check1 = ['$']*len(binary)
		temp = []
		for i in range(len(binary)):
			for j in range(i+1, len(binary)):
				k=compare_string(binary[i], binary[j])
				if k != -1:
					check1[i] = '*'
					check1[j] = '*'
					temp.append(k)
		for  i in range(len(binary)):
			if check1[i] == '$':
				pi.append(binary[i])
		if len(temp) == 0:
			return pi
		binary = list(set(temp))

def decimal_to_binary(no_of_variable, minterms):
	temp = []
	s = ''
	for m in minterms:
		for i in range(no_of_variable):
			s = str(m%2) + s
			m //= 2
		temp.append(s)
		s = ''
	return temp

def is_for_table(string1, string2, count):
	l1 = list(string1);l2=list(string2)
	count_n = 0
	for i in range(len(l1)):
		if l1[i] != l2[i]:
			count_n += 1
	if count_n == count:
		return True
	else:
		return False 

def selection(chart, prime_implicants):
	temp = []
	select = [0]*len(chart)
	for i in range(len(chart[0])):
		count = 0
		rem = -1
		for j in range(len(chart)):
			if chart[j][i] == 1:
				count += 1
				rem = j
		if count == 1:
			select[rem] = 1
	for i in range(len(select)):
		if select[i] == 1:
			for j in range(len(chart[0])):
				if chart[i][j] == 1:
					for k in range(len(chart)):
						chart[k][j] = 0 
			temp.append(prime_implicants[i])
	while 1:
		max_n = 0; rem = -1; count_n = 0
		for i in range(len(chart)):
			count_n = chart[i].count(1)
			if count_n > max_n:
				max_n = count_n
				rem = i
		
		if max_n == 0:
			return temp
		
		temp.append(prime_implicants[rem])
		
		for i in range(len(chart[0])):
			if chart[rem][i] == 1:
				for j in range(len(chart)):
					chart[j][i] = 0
		
def prime_implicant_chart(prime_implicants, binary):
	chart = [[0 for x in range(len(binary))] for x in range(len(prime_implicants))]
	for i in range(len(prime_implicants)):
		count = prime_implicants[i].count('_')
		for j in range(len(binary)):
			if(is_for_table(prime_implicants[i], binary[j], count)):
				chart[i][j] = 1
	
	return chart

def main():
	no_of_variable = int(input("Enter the no. of variables\n"))
	minterms = [int(x) for x in input("Enter the decimal representation of Minterms 'Spaces Seprated'\n").split()]
	binary = decimal_to_binary(no_of_variable, minterms)
	
	prime_implicants = check(binary)
	print("Prime Implicants are:")
	print(prime_implicants)
	chart = prime_implicant_chart(prime_implicants, binary)
	
	essential_prime_implicants = selection(chart,prime_implicants)
	print("Essential Prime Implicants are:")
	print(essential_prime_implicants)

if __name__ == '__main__':
	import doctest
	doctest.testmod()
	main()