Trees.py

from math import log2, pow

class Tree():
	def __init__(this,value=None,left=None,right=None):
		this.value = value
		this.left = left
		this.right = right

tree = Tree('*',
	         Tree('-',
	             Tree('5'),
	             Tree('7')),
	         Tree('+',
		           Tree('3'),
		           Tree('2')))
		
def inorder(tree,n):
	if tree == None:
	  return
	  
	inorder(tree.left,n+1)
	print(str(n)+'-'+tree.value)
	inorder(tree.right,n+1)

def postfix(tree,n):
	if tree == None:
		return
	print('left '+str(n))
	postfix(tree.left,n+1)
	print('right'+str(n))
	postfix(tree.right,n+1)
	print(str(n)+'-'+tree.value)
		
def prefix(tree,n,c,v):
	if tree==None:
		return
	c+=1
	v(tree,n,c)
	prefix(tree.left,n+1,c,v)
	c+=1
	prefix(tree.right,n+1,c,v)
	
def visit(tree,level,count,width=15):
	gap = width//int(pow(2,level))
	linepad = ' '*(gap//2)+'-'*(gap//2)
	pad = ' '*gap
	#print('visit: '+tree.value+' item: '+str(count)+ ' lvl: '+str(level))
	print(pad+'|')
	print(linepad+' '+tree.value)
	
print('Expresssion:')
print('5 * (3 + 2)')
print()
print('Tree:')

print('==Prefix==')
prefix(tree,0,0,visit)