【python刷题】二叉搜索树-相关题目

class Solution:
    def __init__(self):
        self.res = 0
        self.rank = 0

    def kthSmallest(self, root: TreeNode, k: int) -> int:
        self.traverse(root, k)
        return self.res
    
    def traverse(self, root , k):
        if not root:
            return 
        self.traverse(root.left, k)
        self.rank = self.rank + 1
        if self.rank == k:
            self.res = root.val
            return 
        self.traverse(root.right, k)

class Solution:
    def __init__(self):
        self.s = 0
    def convertBST(self, root: TreeNode) -> TreeNode:
        self.traverse(root)
        return root
    def traverse(self, root):
        if not root:
            return 
        self.convertBST(root.right)
        self.s = self.s + root.val
        root.val = self.s
        self.convertBST(root.left)

class Solution:
    def tree2str(self, t: TreeNode) -> str:
        def traverse(root):
            if not root:
                return ""
            if not root.left and not root.right:
                return str(root.val) + ""
            if not root.right:
                return str(root.val) + "(" + traverse(root.left) + ")"
            return str(root.val) + "(" + traverse(root.left) + ")(" + traverse(root.right) + ")
        return traverse(t)

class Solution:
    def __init__(self):
        self.res = float("inf")
        self.pre = -1
    def getMinimumDifference(self, root: TreeNode) -> int:
        def traverse(root):
            if not root:
                return 0
            traverse(root.left)
            if self.pre != -1 and abs(root.val - self.pre) < self.res:
                self.res = abs(root.val - self.pre)
            self.pre = root.val
            traverse(root.right)
        traverse(root)
        return self.res