nfinity means an empty room. We use the value 2^31 - 1 = 2147483647 to represent INF as you may assume that the distance to a gate is less than 2147483647. Fill the empty room with distance to its nearest gate. If it is impossible to reach a gate, it should be filled with INF. For example, given the 2D grid: INF -1 0 INF
Code it output need
You are given a m x n 2D grid 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 2^31 - 1 = 2147483647 to represent INF
as you may assume that the distance to a gate is less than 2147483647.
Fill the empty room with distance to its nearest gate.
If it is impossible to reach a gate, it should be filled with INF.
For example, given the 2D grid:
INF -1 0 INF
INF INF INF -1
INF -1 INF -1
0 -1 INF INF
After running your function, the 2D grid should be:
3 -1 0 1
2 2 1 -1
1 -1 2 -1
0 -1 3 4
"""
def walls_and_gates(rooms):
for i in range(len(rooms)):
for j in range(len(rooms[0])):
if rooms[i][j] == 0:
dfs(rooms, i, j, 0)
def dfs(rooms, i, j, depth):
if (i < 0 or i >= len(rooms)) or (j < 0 or j >= len(rooms[0])):
return # out of bounds
if rooms[i][j] < depth:
return # crossed
rooms[i][j] = depth
dfs(rooms, i+1, j, depth+1)
dfs(rooms, i-1, j, depth+1)
dfs(rooms, i, j+1, depth+1)
dfs(rooms, i, j-1, depth+1).
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