Merge pull request #889 from AlgorithmWithGod/Ukj0ng

[20250914] BOJ / G4 / 일루미네이션 / 한종욱

Author: ShinHeeEul

Ukj0ng/202509/14 BOJ G4 일루미네이션.md

@@ -0,0 +1,104 @@
+```
+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_even = {-1, -1, 0, 0, 1, 1};
+    private static final int[] dy_even = {-1, 0, -1, 1, -1, 0};
+
+    private static final int[] dx_odd = {-1, -1, 0, 0, 1, 1};
+    private static final int[] dy_odd = {0, 1, -1, 1, 0, 1};
+
+    private static int[][] board;
+    private static int W, H, answer;
+
+    public static void main(String[] args) throws IOException {
+        init();
+
+        markOutside();
+
+        for (int i = 1; i <= H; i++) {
+            for (int j = 1; j <= W; j++) {
+                if (board[i][j] == 0) {
+                    board[i][j] = 1;
+                }
+            }
+        }
+
+        for (int i = 1; i <= H; i++) {
+            for (int j = 1; j <= W; j++) {
+                if (board[i][j] == 1) {
+                    answer += countWalls(i, j);
+                }
+            }
+        }
+
+        bw.write(answer + "\n");
+        bw.flush();
+        bw.close();
+        br.close();
+    }
+
+    private static void init() throws IOException {
+        StringTokenizer st = new StringTokenizer(br.readLine());
+        W = Integer.parseInt(st.nextToken());
+        H = Integer.parseInt(st.nextToken());
+
+        board = new int[H+2][W+2];
+
+        for (int i = 1; i <= H; i++) {
+            st = new StringTokenizer(br.readLine());
+            for (int j = 1; j <= W; j++) {
+                board[i][j] = Integer.parseInt(st.nextToken());
+            }
+        }
+    }
+
+    private static void markOutside() {
+        Queue<int[]> q = new ArrayDeque<>();
+        board[0][0] = -1;
+        q.add(new int[]{0, 0});
+
+        while (!q.isEmpty()) {
+            int[] current = q.poll();
+            int x = current[0];
+            int y = current[1];
+
+            int[] dx = (x % 2 == 0) ? dx_even : dx_odd;
+            int[] dy = (x % 2 == 0) ? dy_even : dy_odd;
+
+            for (int i = 0; i < 6; i++) {
+                int nx = x + dx[i];
+                int ny = y + dy[i];
+
+                if (nx < 0 || nx >= H+2 || ny < 0 || ny >= W+2) continue;
+                if (board[nx][ny] != 0) continue;
+
+                board[nx][ny] = -1;
+                q.add(new int[]{nx, ny});
+            }
+        }
+    }
+
+    private static int countWalls(int x, int y) {
+        int walls = 0;
+
+        int[] dx = (x % 2 == 0) ? dx_even : dx_odd;
+        int[] dy = (x % 2 == 0) ? dy_even : dy_odd;
+
+        for (int i = 0; i < 6; i++) {
+            int nx = x + dx[i];
+            int ny = y + dy[i];
+
+            if (nx < 0 || nx >= H+2 || ny < 0 || ny >= W+2 || board[nx][ny] == -1) {
+                walls++;
+            }
+        }
+
+        return walls;
+    }
+}
+```