def pre_order_expr(tree: BinaryTree):
expr = ''
if tree:
expr = str(tree.getRootValue())
expr = expr + pre_order_expr(tree.getLeftChild())
expr = expr + pre_order_expr(tree.getRightChild())
return expr
def evaluate(tree: BinaryTree):
operators = {
'+': operator.add,
'-': operator.sub,
'*': operator.mul,
'/': operator.truediv,
}
left, right = tree.getLeftChild(), tree.getRightChild()
if left and right:
fn = operators[tree.getRootValue()]
return fn(evaluate(left), evaluate(right))
else:
return tree.getRootValue()
def post_order_expr(tree: BinaryTree):
expr = ''
if tree:
if tree.getLeftChild() and tree.getRightChild():
expr = '(' + post_order_expr(tree.getLeftChild())
expr = expr + post_order_expr(tree.getRightChild())
expr = expr + str(tree.getRootValue()) + ')'
else:
expr = post_order_expr(tree.getLeftChild())
expr = expr + post_order_expr(tree.getRightChild())
expr = expr + str(tree.getRootValue())
return expr
def build_parse_tree(expr: str) -> BinaryTree:
expr, stack, bt = list(expr.replace(' ', '')), Stack(), BinaryTree('')
stack.push(bt)
tree = bt
for i in expr:
if i == '(':
tree.insertLeft('')
stack.push(tree)
tree = tree.getLeftChild()
elif i in '1234567890':
tree.setRootValue(eval(i))
tree = stack.pop()
elif i in '+-*/':
tree.setRootValue(i)
tree.insertRight('')
stack.push(tree)
tree = tree.getRightChild()
elif i == ')':
tree = stack.pop()
else:
raise ValueError('Unknown operator: ' + i)
return bt
def setUp(self) -> None:
self.bt = BinaryTree('a')
class TestBinaryTree(unittest.TestCase):
def setUp(self) -> None:
self.bt = BinaryTree('a')
def testRootValue(self):
self.assertEqual('a', self.bt.getRootValue())
def testGetLeftChild(self):
self.assertEqual(None, self.bt.getLeftChild())
def testGetRightChild(self):
self.assertEqual(None, self.bt.getRightChild())
def testBinaryTreeInsertLeftAndRight(self):
self.bt.insertLeft('b')
self.assertEqual('b', self.bt.getLeftChild().getRootValue())
self.bt.insertRight('c')
self.assertEqual('c', self.bt.getRightChild().getRootValue())
self.bt.setRootValue('Hello World')
self.assertEqual('Hello World', self.bt.getRootValue())
self.bt.getRightChild().setRootValue('PRC')
self.assertEqual('PRC', self.bt.getRightChild().getRootValue())
self.bt.getLeftChild().insertLeft('d')
self.assertEqual('d',
self.bt.getLeftChild().getLeftChild().getRootValue())