Link to problem Description 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 k...

This post is about some C++ code snippets that might be useful when doing online assessment (and this post might continue to grow). Sometimes we just couldn’t remember how to do a certain operation...

Link to problem Description Given a string s which represents an expression, evaluate this expression and return its value. The integer division should truncate toward zero. You may assume that...

Link to problem Description You are given the root of a binary tree containing digits from 0 to 9 only. Each root-to-leaf path in the tree represents a number. For example, the root-to-leaf ...

Link to problem Description Implement a SnapshotArray that supports the following interface: SnapshotArray(int length) initializes an array-like data structure with the given length. Initiall...

Link to problem Description You are given an integer array ranks representing the ranks of some mechanics. ranks$_\text{i}$ is the rank of the i$^\text{th}$ mechanic. A mechanic with a rank r can...

Link to problem Description You are given a 0-indexed integer array nums representing the initial positions of some marbles. You are also given two 0-indexed integer arrays moveFrom and moveTo of...

Link to problem Description Given a 0-indexed integer array nums, return the number of distinct quadruplets (a, b, c, d) such that: nums[a] + nums[b] + nums[c] == nums[d], and a < b <...

Link to problem Description Given the root of a binary tree, return the number of nodes where the value of the node is equal to the average of the values in its subtree. Note: The average of ...

Link to problem Description You are given an array prices where prices[i] is the price of a given stock on the ith day. You want to maximize your profit by choosing a single day to buy one stock...