import heapq

class node:
	def __init__(self, freq, symbol, left=None, right=None):
	
		self.freq = freq

		self.symbol = symbol

		self.left = left

		self.right = right

		self.huff = ''
		
	def __lt__(self, nxt):
		return self.freq < nxt.freq
		
def printNodes(node, val=''):
	
	newVal = val + str(node.huff)

	if(node.left):
		printNodes(node.left, newVal)
	if(node.right):
		printNodes(node.right, newVal)

	if(not node.left and not node.right):
		print(f"{node.symbol} -> {newVal}")


chars = ['a', 'b', 'c', 'd', 'e', 'f']

freq = [ 4, 7, 12, 14, 35, 72]

nodes = []

for x in range(len(chars)):
	heapq.heappush(nodes, node(freq[x], chars[x]))

while len(nodes) > 1:
	
	left = heapq.heappop(nodes)
	right = heapq.heappop(nodes)

	left.huff = 0
	right.huff = 1

	newNode = node(left.freq+right.freq, left.symbol+right.symbol, left, right)

	heapq.heappush(nodes, newNode)

printNodes(nodes[0])