# BOJ - 4179 - 불!

Updated:

``````import sys
from collections import deque

def BFS(fire, person, R, C, maps, visit):
dx = [0, 0, -1, 1]
dy = [1, -1, 0, 0]

while person:
temp = deque()
while person:
x, y, time = person.popleft()
if maps[x][y] == "F":
continue

if x == 0 or x == R-1 or y == 0 or y == C-1:
if maps[x][y] != "F": return maps[x][y]

for i in range(4):
nx = x + dx[i]
ny = y + dy[i]
if 0 <= nx < R and 0 <= ny < C:
if maps[nx][ny] == "." and maps[nx][ny] != "F":
maps[nx][ny] = time + 1
temp.append((nx, ny, time + 1))
person = temp

temp = deque()
while fire:
x, y = fire.popleft()

for i in range(4):
nx = x + dx[i]
ny = y + dy[i]
if 0 <= nx < R and 0 <= ny < C:
if visit[nx][ny] == False and maps[nx][ny] != "#":
maps[nx][ny] = "F"
visit[nx][ny] = True
temp.append((nx, ny))
fire = temp
return "IMPOSSIBLE"

def solution():
maps = []
fire = deque()
person = deque()

R, C = map(int, sys.stdin.readline().split())
visit = [[False] * C for _ in range(R)]

for _ in range(R):

for i in range(R):
for j in range(C):
if maps[i][j] == "J":
person.append((i, j, 1))
maps[i][j] = 1
elif maps[i][j] == "F":
fire.append((i, j))
visit[i][j] = True
print(BFS(fire, person, R, C, maps, visit))

solution()
``````

https://www.acmicpc.net/problem/4179

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