Python实现查找二叉搜索树第k大的节点功能示例

class TreeNode:  def __init__(self, x):    self.val = x    self.left = None    self.right = Noneclass Solution:  def __init__(self):    self.k = 0  def recursionKthNode(self, Root):    result = None    if result == None and Root.left:      result = self.recursionKthNode(Root.left)    if result == None:      if self.k == 1:        return Root      self.k -= 1    if result == None and Root.right:      result = self.recursionKthNode(Root.right)    return result  def KthNode(self, Root, k):    if Root == None:      return None    self.k = k    return self.recursionKthNode(Root)Root = TreeNode(5)Root.left = TreeNode(3)Root.left.left = TreeNode(2)Root.left.right = TreeNode(4)Root.right = TreeNode(7)Root.right.left = TreeNode(6)Root.right.right = TreeNode(8)print(Solution().KthNode(Root,3).val)

class TreeNode:  def __init__(self, x):    self.val = x    self.left = None    self.right = Noneclass Solution:  def __init__(self):    self.k = 0  def InOrder(self, Root):    ans = None    if Root:      if ans == None and Root.left:        ans = self.InOrder(Root.left)  #往左遍历      if ans == None and self.k == 1:        ans = Root           #遍历到目标节点      if ans == None and self.k != 1:   #没有遍历到目标节点，k--        self.k -= 1      if ans == None and Root.right:   #往右遍历        ans = self.InOrder(Root.right)    return ans  def KthNode(self, Root, k):    if Root == None or k <= 0:      return None    self.k = k    return self.InOrder(Root)