先序遍歷(遞歸)
def preOrderTraverse(node):
if node is None:
return None
print(node.val)
preOrderTraverse(node.left)
preOrderTraverse(node.right)
先序遍歷(非遞歸)
def preOrderTravese(node):
stack = [node]
while len(stack) > 0:
print(node.val)
if node.right is not None:
stack.append(node.right)
if node.left is not None:
stack.append(node.left)
node = stack.pop()
中序遍歷(遞歸)
def inOrderTraverse(node):
if node is None:
return None
inOrderTraverse(node.left)
print(node.val)
inOrderTraverse(node.right)
中序遍歷(非遞歸)
def inOrderTraverse(node):
stack = []
pos = node
while pos is not None or len(stack) > 0:
if pos is not None:
stack.append(pos)
pos = pos.left
else:
pos = stack.pop()
print(pos.val)
pos = pos.right
後序遍歷(遞歸)
def postOrderTraverse(node):
if node is None:
return None
postOrderTraverse(node.left)
postOrderTraverse(node.right)
print(node.val)
後序遍歷(非遞歸)
# 後序打印二叉樹(非遞歸)
# 使用兩個棧結構
# 第一個棧進棧順序:左節點->右節點->跟節點
# 第一個棧彈出順序: 跟節點->右節點->左節點(先序遍歷棧彈出順序:跟->左->右)
# 第二個棧存儲爲第一個棧的每個彈出依次進棧
# 最後第二個棧依次出棧
def postOrderTraverse(node):
stack = [node]
stack2 = []
while len(stack) > 0:
node = stack.pop()
stack2.append(node)
if node.left is not None:
stack.append(node.left)
if node.right is not None:
stack.append(node.right)
while len(stack2) > 0:
print(stack2.pop().val)
二叉樹節點個數
def treeNodenums(node):
if node is None:
return 0
nums = treeNodenums(node.left)
nums += treeNodenums(node.right)
return nums + 1