python实现leetcode之106. 从中序与后序遍历序列构造二叉树

解题思路

除了跟节点在是后续遍历的最后一个元素以外，其他的与上一题完全一致，不用细说

106. 从中序与后序遍历序列构造二叉树

代码

# Definition for a binary tree node.
# class TreeNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution(object):
    def buildTree(self, inorder, postorder):
        """
        :type inorder: List[int]
        :type postorder: List[int]
        :rtype: TreeNode
        """
        if not postorder:
            return None
        root_val = postorder[-1]
        idx = inorder.index(root_val)
        root = TreeNode(root_val)
        root.left = self.buildTree(inorder[0:idx], postorder[0:idx])
        root.right = self.buildTree(inorder[idx+1:], postorder[idx:-1])
        return root

效果图