Update 0654.最大二叉树.md

This commit is contained in:
jianghongcheng
2023-05-09 14:04:22 -05:00
committed by GitHub
parent 40f8230fd8
commit 7eea41ee0e

View File

@ -259,52 +259,70 @@ class Solution {
```
### Python
(版本一) 基础版
```python
# 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:
"""递归法 更快"""
def constructMaximumBinaryTree(self, nums: List[int]) -> TreeNode:
if not nums:
return None
maxvalue = max(nums)
index = nums.index(maxvalue)
root = TreeNode(maxvalue)
left = nums[:index]
right = nums[index + 1:]
root.left = self.constructMaximumBinaryTree(left)
root.right = self.constructMaximumBinaryTree(right)
return root
if len(nums) == 1:
return TreeNode(nums[0])
node = TreeNode(0)
# 找到数组中最大的值和对应的下标
maxValue = 0
maxValueIndex = 0
for i in range(len(nums)):
if nums[i] > maxValue:
maxValue = nums[i]
maxValueIndex = i
node.val = maxValue
# 最大值所在的下标左区间 构造左子树
if maxValueIndex > 0:
new_list = nums[:maxValueIndex]
node.left = self.constructMaximumBinaryTree(new_list)
# 最大值所在的下标右区间 构造右子树
if maxValueIndex < len(nums) - 1:
new_list = nums[maxValueIndex+1:]
node.right = self.constructMaximumBinaryTree(new_list)
return node
```
(版本二) 使用下标
class Solution:
"""最大二叉树 递归法"""
def traversal(self, nums: List[int], left: int, right: int) -> TreeNode:
if left >= right:
return None
maxValueIndex = left
for i in range(left + 1, right):
if nums[i] > nums[maxValueIndex]:
maxValueIndex = i
root = TreeNode(nums[maxValueIndex])
root.left = self.traversal(nums, left, maxValueIndex)
root.right = self.traversal(nums, maxValueIndex + 1, right)
return root
def constructMaximumBinaryTree(self, nums: List[int]) -> TreeNode:
return self.traversal(nums, 0, len(nums))
def traversal(self, nums: List[int], begin: int, end: int) -> TreeNode:
# 列表长度为0时返回空节点
if begin == end:
return None
# 找到最大的值和其对应的下标
max_index = begin
for i in range(begin, end):
if nums[i] > nums[max_index]:
max_index = i
# 构建当前节点
root = TreeNode(nums[max_index])
# 递归构建左右子树
root.left = self.traversal(nums, begin, max_index)
root.right = self.traversal(nums, max_index + 1, end)
return root
```
(版本三) 使用切片
class Solution:
def constructMaximumBinaryTree(self, nums: List[int]) -> TreeNode:
if not nums:
return None
max_val = max(nums)
max_index = nums.index(max_val)
node = TreeNode(max_val)
node.left = self.constructMaximumBinaryTree(nums[:max_index])
node.right = self.constructMaximumBinaryTree(nums[max_index+1:])
return node
```
### Go