[20251212] BOJ / G4 / 백룸 / 김민진

zinnnn37/202512/12 BOJ G4 백룸.md

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+```java
+import java.io.*;
+import java.util.Arrays;
+import java.util.StringTokenizer;
+
+public class BJ_26259_백룸 {
+
+    private static final int             INF = -987654321;
+    private static final BufferedReader  br  = new BufferedReader(new InputStreamReader(System.in));
+    private static final BufferedWriter  bw  = new BufferedWriter(new OutputStreamWriter(System.out));
+    private static       StringTokenizer st;
+
+    private static int N, M;
+    private static boolean isHorizontal;
+    private static int[][] matrix, dp;
+    private static boolean[][] wall;
+
+    public static void main(String[] args) throws IOException {
+        init();
+        sol();
+    }
+
+    private static void init() throws IOException {
+        st = new StringTokenizer(br.readLine());
+        N = Integer.parseInt(st.nextToken());
+        M = Integer.parseInt(st.nextToken());
+
+        matrix = new int[N + 1][M + 1];
+        for (int i = 1; i <= N; i++) {
+            st = new StringTokenizer(br.readLine());
+            for (int j = 1; j <= M; j++) {
+                matrix[i][j] = Integer.parseInt(st.nextToken());
+            }
+        }
+
+        dp = new int[N + 1][M + 1];
+        for (int[] d : dp) Arrays.fill(d, INF);
+        dp[1][1] = matrix[1][1];
+
+        wall = new boolean[N + 1][M + 1];
+        st = new StringTokenizer(br.readLine());
+        int x1 = Integer.parseInt(st.nextToken());
+        int y1 = Integer.parseInt(st.nextToken());
+        int x2 = Integer.parseInt(st.nextToken());
+        int y2 = Integer.parseInt(st.nextToken());
+
+        if (x1 == x2 && y1 == y2) return;
+
+        isHorizontal = (x1 == x2);
+
+        if (isHorizontal && x1 < N) {
+            int start = Math.min(y1, y2) + 1;
+            int end   = Math.max(y1, y2);
+            for (int y = start; y <= end; y++) {
+                wall[x1 + 1][y] = true;
+            }
+        } else if (!isHorizontal && y1 < M) {
+            int start = Math.min(x1, x2) + 1;
+            int end   = Math.max(x1, x2);
+            for (int x = start; x <= end; x++) {
+                wall[x][y1 + 1] = true;
+            }
+        }
+    }
+
+    private static void sol() throws IOException {
+        for (int i = 1; i <= N; i++) {
+            for (int j = 1; j <= M; j++) {
+                if (i == 1 && j == 1) continue;
+
+                if (wall[i][j]) {
+                    if (isHorizontal && dp[i][j - 1] != INF) {
+                        dp[i][j] = matrix[i][j] + dp[i][j - 1];
+                    } else if (!isHorizontal && dp[i - 1][j] != INF) {
+                        dp[i][j] = matrix[i][j] + dp[i - 1][j];
+                    }
+                } else {
+                    int up   = dp[i - 1][j];
+                    int left = dp[i][j - 1];
+                    if (up != INF || left != INF) {
+                        dp[i][j] = matrix[i][j] + Math.max(up, left);
+                    }
+                }
+            }
+        }
+
+        bw.write(dp[N][M] == INF ? "Entity" : String.valueOf(dp[N][M]));
+        bw.flush();
+        bw.close();
+        br.close();
+    }
+
+}
+```