You are given an m x n grid rooms initialized with these three possible values: - -1 A wall or an obstacle. - 0 A gate. - INF Infinity means an empty room. We use the value 231 - 1 = 2147483647 to represent INF as you may assume that the distance to a gate is less than 2147483647. Fill each empty room with the distance to its nearest gate. If it is impossible to reach a gate, it should be filled with INF.