更新 513.找树左下角的值 python部分代码

1. 上一版本 递归python代码跟题解的方式不同. 个人认为不同方法做出的代码没有必要放在题解里, 建议修改成我提供的python版本.
2. 增加Python3 迭代部分的代码.
This commit is contained in:
Kelvin
2021-07-29 11:25:33 -04:00
parent ff3875d502
commit 49d55fb1c8

View File

@ -274,27 +274,57 @@ class Solution {
Python
**递归 - 回溯**
```python
//递归法
# Definition for a binary tree node.
# class TreeNode:
# def __init__(self, val=0, left=None, right=None):
# self.val = val
# self.left = left
# self.right = right
class Solution:
def findBottomLeftValue(self, root: TreeNode) -> int:
depth=0
self.res=[]
def level(root,depth):
if not root:return
if depth==len(self.res):
self.res.append([])
self.res[depth].append(root.val)
level(root.left,depth+1)
level(root.right,depth+1)
level(root,depth)
return self.res[-1][0]
max_depth = -float("INF")
max_left_value = -float("INF")
def __traversal(root, left_len):
nonlocal max_depth, max_left_value
if not root.left and not root.right:
if left_len > max_depth:
max_depth = left_len
max_left_value = root.val
return
if root.left:
left_len += 1
__traversal(root.left, left_len)
left_len -= 1
if root.right:
left_len += 1
__traversal(root.right, left_len)
left_len -= 1
return
__traversal(root, 0)
return max_left_value
```
**迭代 - 层序遍历**
```python
class Solution:
def findBottomLeftValue(self, root: TreeNode) -> int:
queue = deque()
if root:
queue.append(root)
result = 0
while queue:
q_len = len(queue)
for i in range(q_len):
if i == 0:
result = queue[i].val
cur = queue.popleft()
if cur.left:
queue.append(cur.left)
if cur.right:
queue.append(cur.right)
return result
```
Go