* Given a binary tree, return the level order traversal of its nodes' values. (ie, from left to right, level by level).

A binary tree is height-balanced if, for every node in the tree, the difference in heights of the left and right subtrees is no more than 1. We use a post-order traversal where, at each node, we first ...

Two months ago, LeetCode was a foreign land I'd only heard whispers about. My coding skills were decent, but "algorithm" to me meant the instructions on my washing machine. Now, after two intense ...

Abstract: Binary Search Trees (BSTs) are fundamental data structures in computer science; because of their implicit key sorting and linked node structure, they provide effective sorting and simple ...

Abstract: As a widely used data structure, graphs are good at characterizing data with internal associations, such as social and biological data. Tree structured data are special and are widely used ...

Given a binary tree, return the values of its boundary in anti-clockwise direction starting from root. Boundary includes left boundary, leaves, and right boundary in order without duplicate nodes.