[20250807] BOJ / G4 / 테트로미노 / 이준희

Author: JHLEE325

JHLEE325/202508/07 BOJ G4 테트로미노.md

@@ -0,0 +1,83 @@
+```java
+import java.io.*;
+import java.util.*;
+
+public class Main {
+
+    static int n, m;
+    static int[][] board;
+    static boolean[][] visited;
+    static int max = 0;
+
+    static final 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];
+        visited = new boolean[n][m];
+
+        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());
+            }
+        }
+
+        for (int r = 0; r < n; r++) {
+            for (int c = 0; c < m; c++) {
+                visited[r][c] = true;
+                dfs(r, c, board[r][c], 1);
+                visited[r][c] = false;
+
+                chkother(r, c);
+            }
+        }
+
+        System.out.println(max);
+    }
+
+    static void dfs(int x, int y, int sum, int depth) {
+        if (depth == 4) {
+            max = Math.max(max, sum);
+            return;
+        }
+
+        for (int d = 0; d < 4; d++) {
+            int nx = x + dir[d][0];
+            int ny = y + dir[d][1];
+
+            if (nx < 0 || ny < 0 || nx >= n || ny >= m || visited[nx][ny]) continue;
+
+            visited[nx][ny] = true;
+            dfs(nx, ny, sum + board[nx][ny], depth + 1);
+            visited[nx][ny] = false;
+        }
+    }
+
+    static void chkother(int x, int y) {
+        int wing = 0;
+        int min = Integer.MAX_VALUE;
+        int sum = board[x][y];
+
+        for (int d = 0; d < 4; d++) {
+            int nx = x + dir[d][0];
+            int ny = y + dir[d][1];
+
+            if (nx < 0 || ny < 0 || nx >= n || ny >= m) continue;
+            wing++;
+            sum += board[nx][ny];
+            min = Math.min(min, board[nx][ny]);
+        }
+
+        if (wing < 3) return;
+        if (wing == 4) sum -= min;
+        max = Math.max(max, sum);
+    }
+}
+
+```