This backtracking question combines 4 patterns in one. (and Bloomberg is known for asking it) Given a 2-D grid of characters `board` and a string `word`, return true if `word` is present in the grid, ...

You must first learn trees before you learn: - Backtracking - Graphs - Implicit Graphs Because once you learn trees, everything after stops feeling random. Here's the order we recommend: 1) Binary ...

Given a collection of candidate numbers (candidates) and a target number (target), find all unique combinations in candidates where the candidate numbers sum to target. Each number in candidates may ...