Leetcode 1091. Shortest Path in Binary Matrix

Given an n×n binary grid where 0s are open and 1s are blocked, return the length (number of cells) of the shortest 8-directionally connected path from (0,0) to (n−1,n−1), or -1 if none exists. Core challenge: find the shortest path in a grid with obstacles—typical solution uses BFS over the 8 neighbors (n ≤ 100).