【leetcode】897. Increasing Order Search Tree

题目如下：

解题思路：我的方法是先用递归的方法找出最左边的节点，接下来再对树做一次递归中序遍历，找到最左边节点后将其设为root，其余节点依次插入即可。

代码如下：

# 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):
    newRoot = None
    current = None
    leftMost = 0
    def traverse(self,node):
        if node.val == self.leftMost:
            self.newRoot = TreeNode(node.val)
            self.current = self.newRoot
        if node.left != None:
            self.traverse(node.left)
            #self.leftMost = node.left.val
        if self.current != None and node.val != self.leftMost:
            self.current.right = TreeNode(node.val)
            self.current = self.current.right
        if node.right != None:
            self.traverse(node.right)

    def increasingBST(self, root):
        """
        :type root: TreeNode
        :rtype: TreeNode
        """
        if root == None:
            return root

        r = root

        while r != None:
            self.leftMost = r.val
            r = r.left
        self.newRoot = None
        self.current = None

        self.traverse(root)
        return self.newRoot