> For the complete documentation index, see [llms.txt](https://cai-sen-se.gitbook.io/leetcode/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://cai-sen-se.gitbook.io/leetcode/1-200/106.-cong-zhong-xu-yu-hou-xu-bian-li-xu-lie-gou-zao-er-cha-shu.md).

# 106. 从中序与后序遍历序列构造二叉树

<https://leetcode-cn.com/problems/construct-binary-tree-from-inorder-and-postorder-traversal/>

## 解法一：递归

和**105**题类似，区别在于后序的-1号元素是中序的根，划分之后递归

```python
class Solution:
    def buildTree(self, inorder: List[int], postorder: List[int]) -> TreeNode:
        if len(inorder) == 0 or len(postorder) == 0:
            return
        root = TreeNode(postorder[-1])
        mid = inorder.index(postorder[-1])
        #以mid为界划分中序
        in_l = inorder[:mid]
        in_r = inorder[mid+1:]
        #以mid为界划分后序
        post_l = postorder[:len(in_l)]
        post_r = postorder[len(in_l):-1]
        #递归构造左右子树
        root.left = self.buildTree(in_l, post_l)
        root.right = self.buildTree(in_r, post_r)
        return root
```