[Leetcode]Problem897. Increasing Order Search Tree-python3解題 @ 蟲匯聚之所

題目:

Given a tree, rearrange the tree in in-order so that the leftmost node in the tree is now the root of the tree, and every node has no left child and only 1 right child.

簡易版本:

中序二元樹從最小到最大。只輸出右節點

解題想法:

找到最小值，從root.right->root.left->root的順序return，去除left

code:

# 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:
    def increasingBST(self, root: TreeNode) -> TreeNode:
        nums=[]
        if not root:
            return
        def MidOrder(root):
            if not root:
                return
            if root.left:
                MidOrder(root.left)
            nums.append(root.val)
            if root.right:
                MidOrder(root.right)
        MidOrder(root)
        Atree=TreeNode(0)
        cur=Atree
        for nums in nums:
            cur.right=TreeNode(nums)
            cur=cur.right
        return Atree.right