Hard
Find all dictionary words present in a board.
Given a board and a list of words, return all words that can be formed by adjacent board traversal.
Examples
Input: board = [["o","a","a","n"],["e","t","a","e"],["i","h","k","r"],["i","f","l","v"]], words = ["oath","pea","eat","rain"]
Output: ["eat","oath"]
Constraints
- A cell may be used once per path