Find Minimum Time Across a Grid

You are given an `n x n` grid of non-negative integers. Each value represents the earliest time at which that cell becomes traversable. You start at the top-left cell `(0, 0)` at time `0` and want to reach the bottom-right cell `(n - 1, n - 1)`. At any time `T`, you may stand on or move into a cell only if its value is less than or equal to `T`. You may move one step at a time in the four cardinal directions: up, down, left, and right. Return the minimum time `T` such that there exists a valid path from the top-left corner to the bottom-right corner. Example: - Input: ``` grid = [ [0, 2], [1, 3] ] ``` - Output: `3` Because you cannot enter the bottom-right cell until time `3`, the earliest feasible path is available at `T = 3`. Discuss possible approaches such as priority queue traversal, binary search with reachability checking, or disjoint set union.