Walls and Gates

class Solution(object):
    def wallsAndGates(self, rooms):
        """
        :type rooms: List[List[int]]
        :rtype: None Do not return anything, modify rooms in-place instead.
        """


        from collections import deque

        INF = 2147483647

        q = deque()

        n, m = len(rooms), len(rooms[0])
        for i in range(n):
            for j in range(m):
                if rooms[i][j] == 0:
                    q.append((i, j))

        count = 1
        while q:
            row, col = q.popleft()

            directions = [
                (row+1, col),
                (row-1, col),
                (row, col+1),
                (row, col-1)
            ]

            for (r, c) in directions:
                if r in range(n) and c in range(m) and rooms[r][c] == INF:
                    q.append((r, c))
                    rooms[r][c] = rooms[row][col] + 1

            count += 1