Nearest Exit in a 2D Grid (BFS)

Given a 2D grid grid where: '.' is an empty cell '+' is a wall and an entrance coordinate entrance = (sr, sc) with grid[sr][sc] == '.'. An exit is any empty cell on the boundary of the grid that is not the entrance. Return the minimum number of steps from the entrance to the nearest exit using 4-direction moves, or -1 if no exit exists. Input grid: R x C character matrix entrance: two integers sr sc Output minimum steps (int) or -1 Constraints 1 <= R, C <= 200 4-directional movement only Examples (see CN section for 5 sample cases) Example Input 3 3 + + . . . . + + + 1 0 Output 2