Longest Increasing Path in a Matrix (#329)
Given an m x n integers matrix, return the length of the longest increasing path in matrix.
From each cell, you can either move in four directions: left, right, up, or down. You may not move diagonally or move outside the boundary (i.e., wrap-around is not allowed).
Company Tags: Google, Facebook
Core Concept: Dynamic Programming, DFS, Memoization