[22.02.22] 2636 - 너비우선탐색

Author: par3k

Python_BOJ_2022/2636.py

@@ -0,0 +1,63 @@
+# 치즈
+from collections import deque
+
+n, m = map(int, input().split())
+graph = [list(map(int, input().split())) for _ in range(n)]
+
+# 전체 치즈 갯수가 몇갠지 맨 처음 카운트
+left_cheese = 0
+for i in range(n):
+    for j in range(m):
+        if graph[i][j] == 1:
+            left_cheese += 1
+
+dx, dy = [-1, 1, 0, 0], [0, 0, -1, 1]
+
+# 치즈 테두리를 너비우선탐색으로 돌며 2로 바꿔준다
+def bfs(cheese):
+    queue = deque()
+    queue.append((0, 0))
+    visited[0][0] = True
+    while queue:
+        x, y = queue.popleft()
+        for i in range(4):
+            nx, ny = x + dx[i], y + dy[i]
+            if 0 <= nx < n and 0 <= ny < m:
+                if not visited[nx][ny]:
+                    visited[nx][ny] = True
+                    if graph[nx][ny] == 1:
+                        graph[nx][ny] = 2
+                        cheese -= 1
+                        # print_graph()
+                    else:
+                        queue.append((nx, ny))
+    return cheese
+
+cnt = 0
+tmp = left_cheese
+
+# def print_graph():
+#     print('===================================================')
+#     for i in range(n):
+#         for j in range(m):
+#             print(graph[i][j], end=' ')
+#         print()
+
+# 테두리 부분 치즈를 없앤다.
+def remove_cheese():
+    for i in range(n):
+        for j in range(m):
+            if graph[i][j] == 2:
+                graph[i][j] = 0
+
+# 치즈의 갯수가 존재하는 동안 계속 탐색
+while left_cheese:
+    visited = [[False] * m for _ in range(n)]
+    left_cheese = bfs(left_cheese)
+    if left_cheese != 0:
+        tmp = left_cheese
+    cnt += 1
+    remove_cheese()
+
+print(cnt)
+print(tmp)