def _constructHelper(self, iStart, iEnd):
if iEnd < iStart:
return None
root = BinaryTree(self._postorder[self.pIndex])
self.pIndex -= 1
if iStart == iEnd:
return root
inIndex = self._inorder.index(root.getRootVal())
root.setRightChild(self._constructHelper(inIndex + 1, iEnd))
root.setLeftChild(self._constructHelper(iStart, inIndex - 1))
return root
def _constructHelper(self, levelorder, inorder):
if not levelorder:
return None
root = BinaryTree(levelorder[0])
if len(levelorder) == 1:
return root
inIndex = inorder.index(root.getRootVal())
left = inorder[:inIndex]
right = inorder[inIndex+1:]
root.setLeftChild(self._constructHelper(self._getSubList(levelorder, left), left))
root.setRightChild(self._constructHelper(self._getSubList(levelorder, right), right))
return root
def _constructHelper(self, iStart, iEnd):
if iStart > iEnd:
return None
root = BinaryTree(self._preorder[self.pIndex])
self.pIndex += 1
if iStart == iEnd:
return root
preIndex = self._postorder.index(self._preorder[self.pIndex])
root.setLeftChild(self._constructHelper(iStart, preIndex))
root.setRightChild(self._constructHelper(preIndex + 1, iEnd - 1))
return root
def buildParseTree(exp):
tree = BinaryTree('')
stack = []
stack.append(tree)
currentTree = tree
exp = exp.split()
for i in exp:
if i == '(':
currentTree.insertLeft('')
stack.append(currentTree)
currentTree = currentTree.getLeftChild()
elif i not in ['+', '-', '*', '/', ')']:
currentTree.setRootVal(i)
currentTree = stack.pop()
elif i in ['+', '-', '*', '/']:
currentTree.insertRight('')
currentTree.setRootVal(i)
stack.append(currentTree)
currentTree = currentTree.getRightChild()
elif i == ')':
currentTree = stack.pop()
else:
raise ValueError
return tree
while numberOfNodes > 0:
node = queue.pop(0)
nodesSameLevel.append(node)
if node.getLeftChild():
queue.append(node.getLeftChild())
if node.getRightChild():
queue.append(node.getRightChild())
numberOfNodes -= 1
print(printNodesByLevel(nodesSameLevel))
def printNodesByLevel(nodes):
values = []
for node in nodes:
values.append(node.getRootVal())
return ' '.join('({:d})'.format(x) for x in values)
tree = BinaryTree(1)
tree.insertLeft(2)
tree.insertRight(3)
tree.getLeftChild().insertLeft(4)
tree.getLeftChild().insertRight(5)
tree.getRightChild().insertRight(6)
printEachTreeLevel(tree)
# print nodes in ascending order
if tree:
inorder(tree.getLeftChild())
print(tree.getRootVal())
inorder(tree.getRightChild())
def preorder(tree):
# print root node first
if tree:
print(tree.getRootVal())
preorder(tree.getLeftChild())
preorder(tree.getRightChild())
tree = BinaryTree(2)
tree.insertLeft(1)
tree.insertRight(3)
tree.getLeftChild().insertLeft(0)
tree.getLeftChild().insertLeft(7)
tree.getRightChild().insertLeft(9)
tree.getRightChild().insertRight(1)
"""
2
/ \
1 3
/ \ / \
0 7 9 1
"""
preorder(tree)