Trees

Mirror a binary tree.

Given the head of a singly linked list and two integers left and right where left <= right, reverse the nodes of the list from position left to position right, and return _the reversed lis

Given the root of a binary tree and an integer targetSum, return _all root-to-leaf paths where the sum of the node values in the path equals_ targetSum_. Each path should be returned as a li

You are given a doubly linked list, which contains nodes that have a next pointer, a previous pointer, and an additional child pointer. This child pointer may or may not point to a separate doubly

Design an algorithm to encode an N-ary tree into a binary tree and decode the binary tree to get the original N-ary tree. An N-ary tree is a rooted tree in which each node has no more than N children.

You are given two non-empty linked lists representing two non-negative integers. The most significant digit comes first and each of their nodes contains a single digit. Add the two numbers and ret

Given the root of 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 the sum of all keys greater than the original k

Given the root of a binary search tree and the lowest and highest boundaries as low and high, trim the tree so that all its elements lies in [low, high]. Trimming the tree should not chang

Given a non-empty special binary tree consisting of nodes with the non-negative value, where each node in this tree has exactly two or zero sub-node. If the node has two sub-nodes, then this node'

You are given the root node of a binary search tree (BST) and a value to insert into the tree. Return _the root node of the BST after the insertion_. It is guaranteed that the new value does n

Given a Circular Linked List node, which is sorted in non-descending order, write a function to insert a value insertVal into the list such that it remains a sorted circular list. The given node can

Given the root of a binary search tree, rearrange the tree in in-order so that the leftmost node in the tree is now the root of the tree, and every node has no left child and only one right chil

You are given the root of a binary tree with n nodes, where each node is uniquely assigned a value from 1 to n. You are also given a sequence of n values voyage, which is the desired [

Given the root of a binary tree with unique values and the values of two different nodes of the tree x and y, return true _if the nodes corresponding to the values_ x _and_ y _in the tree

Given the root of 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 the sum of all keys greater than the original k

Given the edges of a directed graph where edges[i] = [ai, bi] indicates there is an edge between nodes ai and bi, and two nodes source and destination of this graph, determine whether or n

Two players play a turn based game on a binary tree. We are given the root of this binary tree, and the number of nodes n in the tree. n is odd, and each node has a distinct value from 1 to `n

Given the roots of two binary search trees, root1 and root2, return true if and only if there is a node in the first tree and a node in the second tree whose values sum up to a given integer `ta

You have n binary tree nodes numbered from 0 to n - 1 where node i has two children leftChild[i] and rightChild[i], return true if and only if all the given nodes form **exactly one*

There are n cities numbered from 0 to n - 1 and n - 1 roads such that there is only one way to travel between two different cities (this network form a tree). Last year, The ministry of transp

You are given an undirected weighted graph of n nodes (0-indexed), represented by an edge list where edges[i] = [a, b] is an undirected edge connecting the nodes a and b with a probability of

You are given the root of a binary tree and an integer distance. A pair of two different leaf nodes of a binary tree is said to be good if the length of the shortest path between them is l

Given the root of a binary tree and a node u in the tree, return _the nearest node on the same level that is to the right of_ u_, or return_ null _if_ u _is the rightmost node in

A [binary expression tree](https://en.wikipedia.org/wiki/Binary_expression_tree) is a kind of binary tree used to represent arithmetic expressions. Each node of a binary expression tree has either

Given the root of a binary tree, return _the lowest common ancestor (LCA) of two given nodes,_ p _and_ q. If either node p or q does not exist in the tree, return null. All values of t

An undirected graph of n nodes is defined by edgeList, where edgeList[i] = [ui, vi, disi] denotes an edge between nodes ui and vi with distance disi. Note that there may be multiple ed

In a garden represented as an infinite 2D grid, there is an apple tree planted at every integer coordinate. The apple tree planted at an integer coordinate (i, j) has |i| + |j| apples growing

Given the head of a singly linked list that is sorted in non-decreasing order using the absolute values of its nodes, return _the list sorted in non-decreasing order using the **actual v

Find max depth of binary tree.

Longest path between any two nodes.

Check if tree is height-balanced.

Check if two trees are identical.

Check if tree contains subtree.

Find LCA in BST.

Level-order traversal values.

Values visible from right side.

Count nodes with no greater ancestor.

Check if valid BST.

Find kth smallest in BST.

Build tree from traversals.

Max path sum in binary tree.

Serialize/deserialize binary tree.