diff --git "a/JHLEE325/202508/06 BOJ G4 \354\227\260\352\265\254\354\206\214.md" "b/JHLEE325/202508/06 BOJ G4 \354\227\260\352\265\254\354\206\214.md" new file mode 100644 index 00000000..b6f7456f --- /dev/null +++ "b/JHLEE325/202508/06 BOJ G4 \354\227\260\352\265\254\354\206\214.md" @@ -0,0 +1,99 @@ +```java +import java.io.*; +import java.util.*; + +public class Main { + + static int n, m; + static int[][] board; + static int maxSafe = 0; + static int[][] dir = {{-1, 0}, {1, 0}, {0, -1}, {0, 1}}; + + public static void main(String[] args) throws Exception { + BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); + StringTokenizer st; + + st = new StringTokenizer(br.readLine()); + n = Integer.parseInt(st.nextToken()); + m = Integer.parseInt(st.nextToken()); + + board = new int[n][m]; + List empties = new ArrayList<>(); + List viruses = new ArrayList<>(); + + for (int r = 0; r < n; r++) { + st = new StringTokenizer(br.readLine()); + for (int c = 0; c < m; c++) { + board[r][c] = Integer.parseInt(st.nextToken()); + if (board[r][c] == 0) empties.add(r * m + c); + else if (board[r][c] == 2) viruses.add(r * m + c); + } + } + + int E = empties.size(); + + for (int i = 0; i < E; i++) { + for (int j = i + 1; j < E; j++) { + for (int k = j + 1; k < E; k++) { + int[][] tmp = copyBoard(board); + + placeWall(tmp, empties.get(i)); + placeWall(tmp, empties.get(j)); + placeWall(tmp, empties.get(k)); + + spreadVirus(tmp, viruses); + + int safe = countSafe(tmp); + if (safe > maxSafe) maxSafe = safe; + } + } + } + + System.out.println(maxSafe); + } + + static int[][] copyBoard(int[][] src) { + int[][] dst = new int[n][m]; + for (int r = 0; r < n; r++) { + System.arraycopy(src[r], 0, dst[r], 0, m); + } + return dst; + } + + static void placeWall(int[][] g, int pos) { + int r = pos / m, c = pos % m; + g[r][c] = 1; + } + + static void spreadVirus(int[][] g, List viruses) { + ArrayDeque q = new ArrayDeque<>(); + for (int v : viruses) { + int vr = v / m, vc = v % m; + q.add(new int[]{vr, vc}); + } + while (!q.isEmpty()) { + int[] cur = q.poll(); + int y = cur[0], x = cur[1]; + for (int d = 0; d < 4; d++) { + int dy = y + dir[d][0], dx = x + dir[d][1]; + if (dy < 0 || dy >= n || dx < 0 || dx >= m) continue; + if (g[dy][dx] == 0) { + g[dy][dx] = 2; + q.add(new int[]{dy, dx}); + } + } + } + } + + static int countSafe(int[][] g) { + int cnt = 0; + for (int r = 0; r < n; r++) { + for (int c = 0; c < m; c++) { + if (g[r][c] == 0) cnt++; + } + } + return cnt; + } +} + +```