给一个Binary Tree,检查是不是Binary Search Tree. 即是否满足对每个节点,左子树的中的所有节点的值 < 当前节点的值 < 右子树所有节点的值. Solution #1, 用中序遍历.因为中序遍历是DFS的一种,Time complexity: O(N), space complexity: O(logN) public class Solution { int lastCheck = Integer.MIN_VALUE; public boolean isValid…

Given a binary tree, find the largest subtree which is a Binary Search Tree (BST), where largest means subtree with largest number of nodes in it. Note:A subtree must include all of its descendants.Here's an example: 10 / \ 15 / \ \ 1 8 7 The Largest…

Given a binary tree, find the largest subtree which is a Binary Search Tree (BST), where largest means subtree with largest number of nodes in it. Note: A subtree must include all of its descendants. Here's an example: 10 / \ 5 15 / \ \ 1 8 7 The Lar…

Given a binary tree, determine if it is a valid binary search tree (BST). Assume a BST is defined as follows: The left subtree of a node contains only nodes with keys less than the node's key. The right subtree of a node contains only nodes with keys…

Given a Binary Search Tree (BST), convert it to a Greater Tree such that every key of the original BST is changed to the original key plus sum of all keys greater than the original key in BST. Example: Input: The root of a Binary Search Tree like thi…

Given a Binary Search Tree (BST) with root node root, and a target value V, split the tree into two subtrees where one subtree has nodes that are all smaller or equal to the target value, while the other subtree has all nodes that are greater than th…

Validate Binary Search Tree Given a binary tree, determine if it is a valid binary search tree (BST). Assume a BST is defined as follows: The left subtree of a node contains only nodes with keys less than the node's key.The right subtree of a node co…

Implement a function to check if a binary tree is a binary search tree. 这道题很经典,让我们判断一棵树是不是二叉查找树.但是首先要确定一下二叉查找树的定义,比如leetcode 98题中的定义左<根<右就可以直接通过判断中序遍历是不是有序序列就可以了.但是一般的BST定义的是左<=根<右,就不可以用这种方法来判断. 如果是如上定义,直接根据定义递归的检查下每一个node是否满足定义就可以了,如下: (对于roo…

In this problem, your job to write a function to check whether a input string is a valid IPv4 address or IPv6 address or neither. IPv4 addresses are canonically represented in dot-decimal notation, which consists of four decimal numbers, each ranging…

Given a binary tree, determine if it is a valid binary search tree (BST). Assume a BST is defined as follows: The left subtree of a node contains only nodes with keys less than the node's key. The right subtree of a node contains only nodes with keys…