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binaryTreePaths.py
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binaryTreePaths.py
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#!/usr/bin/env python
# -*- encoding: utf-8 -*-
'''
@File : binaryTreePaths.py
@Time : 2024/10/11 20:10:30
@Author : Zihao Zheng
@Email : [email protected]
'''
class TreeNode:
def __init__(self, val=0, left=None, right=None):
self.val = val
self.left = left
self.right = right
Node1=TreeNode(val=3)
Node2=TreeNode(val=9)
Node3=TreeNode(val=20)
Node4=TreeNode(val=15)
Node5=TreeNode(val=7)
Node1.left=Node2
Node1.right=Node3
Node3.left=Node4
Node3.right=Node5
Node6=TreeNode(val=1)
Node7=TreeNode(val=2)
Node8=TreeNode(val=2)
Node9=TreeNode(val=3)
Node10=TreeNode(val=3)
Node11=TreeNode(val=4)
Node12=TreeNode(val=4)
Node6.left=Node7
Node6.right=Node8
Node7.left=Node9
Node7.right=Node10
Node9.left=Node11
Node9.right=Node12
def traversal( cur, path, result):
path.append(cur.val) # 中
if not cur.left and not cur.right: # 到达叶子节点
sPath = '->'.join(map(str, path))
result.append(sPath)
return
if cur.left: # 左
traversal(cur.left, path, result)
path.pop() # 回溯
if cur.right: # 右
traversal(cur.right, path, result)
path.pop() # 回溯
def binaryTreePaths( root):
result = []
path = []
if not root:
return result
traversal(root, path, result)
def binaryTreePaths2( root): #前序遍历
node_stack,path_stack,result=[root],[str(root.val)],[]
while node_stack:
cur_node=node_stack.pop()
cur_path=path_stack.pop()
if (cur_node.left is None) and (cur_node.right is None):#not （cur_node.left or cur_node.leftcur_node.right）
result.append(cur_path)
if cur_node.right:
node_stack.append(cur_node.right)
path_stack.append(cur_path+'->'+str(cur_node.right.val))
if cur_node.left:
node_stack.append(cur_node.left)
path_stack.append(cur_path+'->'+str(cur_node.left.val))
return result
binaryTreePaths(Node1)
class Solution:
def traversal(self, cur, path, result):
path.append(cur.val) # 中 #借栈
if not cur.left and not cur.right: # 到达叶子节点
sPath = '->'.join(map(str, path))
result.append(sPath)
return
if cur.left: # 左
self.traversal(cur.left, path, result)
path.pop() # 回溯
if cur.right: # 右
self.traversal(cur.right, path, result)
path.pop() # 回溯
def binaryTreePaths(self, root):
result = []
path = []
if not root:
return result
self.traversal(root, path, result)
return result
def binaryTreePaths2(self, root):
node_stack,path_stack,result=[root],[str(root.value)],[]
while node_stack:
cur_node=node_stack.pop()
cur_path=path_stack.pop()
if (cur_node.left is None) and (cur_node.right is None):#not （cur_node.left or cur_node.leftcur_node.right）
result.append(cur_path)
if cur_node.right:
node_stack.append(cur_node.right)
path_stack.append(cur_path+'->'+str(cur_node.right.value))
if cur_node.left:
node_stack.append(cur_node.left)
path_stack.append(cur_path+'->'+str(cur_node.left.value))
return result
return