输入某二叉树的前序遍历和中序遍历的结果,请重建该二叉树。假设输入的前序遍历和中序遍历的结果中都不含重复的数字。
例如,给出
前序遍历 preorder = [3,9,20,15,7]
中序遍历 inorder = [9,3,15,20,7]
返回如下的二叉树:
3
/ \
9 20
/ \
15 7
来源:力扣(LeetCode)
链接:https://leetcode-cn.com/problems/zhong-jian-er-cha-shu-lcof
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我的解答:
# Definition for a binary tree node.
# class TreeNode:
# def __init__(self, x):
# self.val = x
# self.left = None
# self.right = None
class Solution:
def buildTree(self, preorder: List[int], inorder: List[int]) -> TreeNode:
def buildtree(preorder: List[int], inorder: List[int]) -> TreeNode:
if len(preorder) > 0 and preorder[0] in inorder:
n = preorder[0]
root = TreeNode(n)
root_idx = inorder.index(n)
else:
return None
preorder.remove(n)
root.left = buildtree(preorder, inorder[:root_idx])
root.right = buildtree(preorder, inorder[root_idx+1:])
return root
return buildtree(preorder, inorder)
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