20200329-劍指offer-面試題54. 二叉搜索樹的第k大節點

傳送門
分析：二插搜索樹的中序遍歷結果是有序的，中序遍歷的結果放在列表中，返回list[-k]即可。

class Solution(object):
    def kthLargest(self, root, k):
        """
        :type root: TreeNode
        :type k: int
        :rtype: int
        """
        # 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 kthLargest(self, root, k):
        """
        :type root: TreeNode
        :type k: int
        :rtype: int
        """
        list=[]
        
        def dfs(node):
            if not node:
                return 
            else:
                dfs(node.left)
                list.append(node.val)
                dfs(node.right)
        
        dfs(root)

        # reversed(sorted(list))
        return list[-k]