Cut Off Trees for Golf Event

Given an m x n grid with impassable cells (0), empty cells (1), and trees (>1) with distinct heights, find the minimum number of 4-directional steps starting from (0,0) to cut all trees in strictly increasing height order (cutting a tree turns its cell to 1), or return -1 if any tree is unreachable. The core challenge is computing and summing shortest-path distances between successive trees in height order (typically via repeated BFS/A*).