Update 0654.最大二叉树.md

problems/0654.最大二叉树.md

@@ -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