Find Shortest Grid Path

You are given an `m x n` grid where `0` represents an open cell and `1` represents a blocked cell. You are also given a start cell `(sr, sc)` and a target cell `(tr, tc)`. From any open cell, you may move one step up, down, left, or right, as long as the next cell is inside the grid and not blocked. Return the minimum number of moves required to reach the target from the start. If the target is unreachable, return `-1`. Follow-up: Describe how you could also solve the problem using recursive depth-first search with backtracking and memoization, and explain the tradeoffs compared with a breadth-first search approach.