[20260201] BOJ / G3 / 성곽 / 한종욱

Author: Ukj0ng

Ukj0ng/202602/01 BOJ G3 성곽.md

@@ -0,0 +1,157 @@
+```
+import java.io.*;
+import java.util.*;
+
+public class Main {
+    private static final BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+    private static final BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
+    private static final int[] dx = {0, -1, 0, 1};
+    private static final int[] dy = {-1, 0, 1, 0};
+    private static Map<Integer, Integer> rooms;
+    private static Set<Integer>[] near;
+    private static int[][] arr;
+    private static boolean[][] visited;
+    private static boolean[][][] wall;
+    private static int N, M, answer1, answer2, answer3;
+
+    public static void main(String[] args) throws IOException {
+        init();
+
+        int num = 1;
+
+        for (int i = 0; i < M; i++) {
+            for (int j = 0; j < N; j++) {
+                if (!visited[i][j]) {
+                    BFS(i, j, num++);
+                }
+            }
+        }
+
+        near = new Set[rooms.size()+1];
+
+        for (int i = 1; i <= rooms.size(); i++) {
+            near[i] = new HashSet<>();
+        }
+
+        for (int i = 0; i < M; i++) {
+            Arrays.fill(visited[i], false);
+        }
+
+        for (int i = 0; i < M; i++) {
+            for (int j = 0; j < N; j++) {
+                if (!visited[i][j]) {
+                    setNear(i, j, arr[i][j]);
+                }
+            }
+        }
+
+        answer1 = rooms.size();
+        for (int key : rooms.keySet()) {
+            answer2 = Math.max(answer2, rooms.get(key));
+        }
+
+        for (int i = 1; i <= answer1; i++) {
+            for (int e : near[i]) {
+                answer3 = Math.max(answer3, rooms.get(i)+rooms.get(e));
+            }
+        }
+
+        bw.write(answer1 + "\n" + answer2 + "\n" + answer3);
+        bw.flush();
+        bw.close();
+        br.close();
+    }
+
+    private static void init() throws IOException {
+        StringTokenizer st =  new StringTokenizer(br.readLine());
+        N = Integer.parseInt(st.nextToken());
+        M = Integer.parseInt(st.nextToken());
+
+        arr = new int[M][N];
+        visited = new boolean[M][N];
+        wall = new boolean[M][N][4];
+
+        rooms = new HashMap<>();
+
+        for (int i = 0; i < M; i++) {
+            st = new StringTokenizer(br.readLine());
+            for (int j = 0; j < N; j++) {
+                int temp = Integer.parseInt(st.nextToken());
+
+                if (temp >= 8) {
+                    temp -= 8;
+                    wall[i][j][3] = true;
+                }
+
+                if (temp >= 4) {
+                    temp -= 4;
+                    wall[i][j][2] = true;
+                }
+
+                if (temp >= 2) {
+                    temp -= 2;
+                    wall[i][j][1] = true;
+                }
+
+                if (temp >= 1) {
+                    temp -= 1;
+                    wall[i][j][0] = true;
+                }
+            }
+        }
+    }
+
+    private static void BFS(int x, int y, int index) {
+        Queue<int[]> q = new ArrayDeque<>();
+        int count = 1;
+        visited[x][y] = true;
+        arr[x][y] = index;
+        q.add(new int[] {x, y, index});
+
+        while (!q.isEmpty()) {
+            int[] current = q.poll();
+
+            for (int i = 0; i < 4; i++) {
+                if (wall[current[0]][current[1]][i]) continue;
+                int nx = current[0] + dx[i];
+                int ny = current[1] + dy[i];
+
+                if (OOB(nx, ny) || visited[nx][ny]) continue;
+                visited[nx][ny] = true;
+                count++;
+                arr[nx][ny] = index;
+                q.add(new int[] {nx, ny, index});
+            }
+        }
+
+        rooms.put(index, count);
+    }
+
+    private static void setNear(int x, int y, int index) {
+        Queue<int[]> q = new ArrayDeque<>();
+        visited[x][y] = true;
+        q.add(new int[] {x, y});
+
+        while (!q.isEmpty()) {
+            int[] current = q.poll();
+
+            for (int i = 0; i < 4; i++) {
+                int nx = current[0] + dx[i];
+                int ny = current[1] + dy[i];
+
+                if (OOB(nx, ny) || visited[nx][ny]) continue;
+                if (arr[current[0]][current[1]] != arr[nx][ny]) {
+                    near[index].add(arr[nx][ny]);
+                    continue;
+                }
+                visited[nx][ny] = true;
+                q.add(new int[] {nx, ny});
+            }
+        }
+    }
+
+    private static boolean OOB(int nx, int ny) {
+        return nx < 0 || nx > M-1 || ny < 0 || ny > N-1;
+    }
+}
+```