This is the python solution for the Leetcode problem – Walls and Gates – Leetcode Challenge – Python Solution.

Source – qiyuangong’s repository.

class Solution(object): def wallsAndGates(self, rooms): """ :type rooms: List[List[int]] :rtype: void Do not return anything, modify rooms in-place instead. """ # BFS with queue direction = [(0, 1), (1, 0), (0, -1), (-1, 0)] m = len(rooms) if m == 0: return n = len(rooms[0]) q = [] for row in range(m): for col in range(n): # gate if rooms[row][col] == 0: q.append((row, col)) while len(q) > 0: point = q.pop(0) row, col = point[0], point[1] for d in direction: r = row + d[0] c = col + d[1] # wall or out of rooms if r < 0 or c < 0 or r >= m or c >= n or rooms[r][c] != 2147483647: continue rooms[r][c] = rooms[row][col] + 1 q.append((r, c))