[BOJ] 14502 연구소 (G4)

Author: uiop5809

박예진/0주차/BFS/14502.py

@@ -0,0 +1,73 @@
+import sys
+input = sys.stdin.readline
+from collections import deque
+
+N, M = map(int, input().split())
+arr = [list(map(int, input().split())) for _ in range(N)]
+zeros = []
+dx = [-1, 0, 1, 0]
+dy = [0, 1, 0, -1]
+answer = 0
+
+def OOB(x, y):
+    return x < 0 or x >= N or y < 0 or y >= M
+
+# 바이러스 퍼트리기
+def bfs(temp):
+    q = deque()
+
+    for i in range(N):
+        for j in range(M):
+            if temp[i][j] == 2:
+                q.append((i, j))
+    
+    while q:
+        x, y = q.popleft()
+
+        for dir in range(4):
+            nx = x + dx[dir]
+            ny = y + dy[dir]
+
+            if OOB(nx, ny):
+                continue
+            if temp[nx][ny] == 0:
+                q.append((nx, ny))
+                temp[nx][ny] = 2
+
+# 0인 곳들 중 3개 백트래킹 후, BFS
+wall_idx = []
+def dfs(depth, start):
+    global answer
+
+    if depth == 3:
+        # 깊은 복사
+        temp = [row[:] for row in arr]
+        # 벽 세우기
+        for idx in wall_idx:
+            x, y = zeros[idx]
+            temp[x][y] = 1
+        # 바이러스 퍼트리기
+        bfs(temp)
+        # temp 중 남은 안전지역
+        cnt = 0
+        for i in range(N):
+            for j in range(M):
+                if temp[i][j] == 0:
+                    cnt += 1
+
+        answer = max(answer, cnt)
+        return
+
+    for i in range(start, len(zeros)):
+        wall_idx.append(i)
+        dfs(depth + 1, i + 1)
+        wall_idx.pop()
+
+# 0인 곳 위치 파악
+for i in range(N):
+    for j in range(M):
+        if arr[i][j] == 0:
+            zeros.append((i, j))
+
+dfs(0, 0)
+print(answer)