[LeetCode]Construct Binary Tree from Inorder and Postorder [email protected]

Given inorder and postorder traversal of a tree, construct the binary tree.

Note:

You may assume that duplicates do not exist in the tree.

For example, given

inorder = [9,3,15,20,7]
postorder = [9,15,7,20,3]      

Return the following binary tree:

3
   / \
  9  20
    /  \
   15   7
      

思路：和上题一样，只不过这一次是先填满右子树再填左子树。

# 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 inorder:
            return None
        ind = inorder.index(postorder.pop())
        root = TreeNode(inorder[ind])
        root.right = self.buildTree(inorder[ind+1:], postorder)
        root.left = self.buildTree(inorder[:ind], postorder)
        return root