def makeparsetree(expression):
now = BinaryTree(None)
parent = Stack()
for item in expression:
if item in openbraket:
now.addleft(None)
parent.push(now)
now = now.getleft()
elif item in endbraket:
if not parent.isEmpty():
now = parent.pop()
elif item in operators:
now.setdata(item)
parent.push(now)
now.addright(None)
now = now.getright()
else :
now.setdata(int(item))
now = parent.pop()
"""else:
return "Invalid expression"""
# print "Read ", item #debug line
return now
from BinaryTree import BinaryTree
def next_node(root):
current = root
if current.right is not None:
current = current.right
while current.left is not None:
current = current.left
return current
# Go up until we find a parent who this is the left subtree of
while current.parent is not None:
if current.parent.left is current:
return current.parent
current = current.parent
if __name__ == '__main__':
root = BinaryTree(4)
root.addleft(BinaryTree(2))
root.left.addright(BinaryTree(3))
root.left.addleft(BinaryTree(1))
root.addright(BinaryTree(6))
print('Expect 3:', next_node(root.left).data)
print('Expect 4:', next_node(root.left.right).data)
# Tree of one node
root = BinaryTree(0)
print('Expect None:', next_node(root))
