Given the root of a binary search tree (BST) with duplicates, return all the mode(s) (i.e., the most frequently occurred element) in it. If the tree has more than one mode, return them in any orde...

Given the root of a binary tree, determine if it is a valid binary search tree (BST). A valid BST is defined as follows: The left subtree of a node contains only nodes with keys less than the nod...

Given the root of a Binary Search Tree (BST), return the minimum absolute difference between the values of any two different nodes in the tree. Example 1: Input: root = [4,2,6,1,3] Output: 1 Exam...

You are given the root of a binary search tree (BST) and an integer val. Find the node in the BST that the node’s value equals val and return the subtree rooted with that node. If such a node does...

You are given two binary trees root1 and root2. Imagine that when you put one of them to cover the other, some nodes of the two trees are overlapped while the others are not. You need to merge the...

You are given an integer array nums with no duplicates. A maximum binary tree can be built recursively from nums using the following algorithm: Create a root node whose value is the maximum value ...

Given the root of a binary tree and an integer targetSum, return true if the tree has a root-to-leaf path such that adding up all the values along the path equals targetSum. A leaf is a node with ...

Find Bottom Left Tree Value Solved Medium Topics Companies Given the root of a binary tree, return the leftmost value in the last row of the tree. Example 1: Input: root = [2,1,3] Output: 1 Exam...

1. 连接到 NCC 在使用 NCC 之前，你需要通过命令行连接到 NCC。建议先查看 Learn Ultra 页面，获取具体的连接方式。通常，你需要通过 SSH 连接： ssh your_username@ncc1.clients.durham.ac.uk 如果 SSH 连接有问题，检查是否需要使用 ProxyCommand 或 ProxyJump（可能需要先连接 hamilton...

Recursion Given the root of a binary tree, return the sum of all left leaves. A leaf is a node with no children. A left leaf is a leaf that is the left child of another node. Example 1: Input: r...