A storekeeper is a game in which the player pushes boxes around in a warehouse trying to get them to target locations.
The game is represented by an m x n grid of characters grid where each element is a wall, floor, or box.
Your task is to move the box 'B' to the target position 'T' under the following rules:
The character 'S' represents the player. The player can move up, down, left, right in grid if it is a floor (empty cell).
The character '.' represents the floor which means a free cell to walk.
The character '#' represents the wall which means an obstacle (impossible to walk there).
There is only one box 'B' and one target cell 'T' in the grid .
The box can be moved to an adjacent free cell by standing next to the box and then moving in the direction of the box. This is a push .
The player cannot walk through the box.
Return the minimum number of pushes to move the box to the target . If there is no way to reach the target, return -1 .
m == grid.lengthn == grid[i].length1 <= m, n <= 20grid contains only characters '.' , '#' , 'S' , 'T' , or 'B' .There is only one character 'S' , 'B' , and 'T' in the grid .