Leetcode 3342. Find Minimum Time to Reach Last Room II

Find the minimum time to reach the bottom-right cell in an n×m grid from (0,0) when each cell has a minimum allowed time you can start moving into it and each move alternates in duration between 1 and 2 seconds (first move = 1s). This is a shortest-path problem with time-dependent edge costs and a parity state (move index mod 2) that determines move length.