Merge pull request #556 from AlgorithmWithGod/0224LJH

[20250727] BOJ / G5 / 사과나무 / 이종환

Author: ShinHeeEul

0224LJH/202507/27 BOJ 사과나무.md

@@ -0,0 +1,83 @@
+```java
+import java.awt.Point;
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.*;
+
+public class Main {
+
+    static long ans;
+    static int size;
+    static long[][] arr,sumArr;
+    static int[] dy = {0,1};
+    static int[] dx = {1,0};
+
+    public static void main(String[] args) throws IOException {
+        init();
+        process();
+        print();
+    }
+
+    private static void init() throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        size = Integer.parseInt(br.readLine());
+        ans = Integer.MIN_VALUE;
+
+        arr = new long[size][size];
+        sumArr = new long[size][size]; // i,j -> 0,0부터 i.j까지 직사각형 하
+        for (int i = 0; i < size; i++) {
+            StringTokenizer st = new StringTokenizer(br.readLine());
+            for (int j = 0; j < size; j++) {
+                arr[i][j] = Long.parseLong(st.nextToken());
+            }
+        }
+    }
+
+    private static void process() throws IOException {
+        makeSumArr();
+
+        for (int i = 0; i < size; i++) {
+            for (int j = 0; j < size; j++) {
+                calculate(i,j);
+            }
+        }
+
+    }
+
+    private static void calculate(int y, int x) {
+        for (int i = 0; i < size; i++) {
+            if ( y - i < 0 || x - i < 0) continue;
+            long cur = sumArr[y][x];
+            if ( y- i > 0) cur -= sumArr[y-i-1][x];
+            if ( x - i > 0 ) cur -= sumArr[y][x-i-1];
+            if ( x-i > 0 && y-i > 0) cur += sumArr[y-i-1][x-i-1];
+
+            ans = Math.max(ans, cur);
+        }
+
+    }
+
+    private static void makeSumArr() {
+
+        for (int i = 0; i < size; i++) {
+            for (int j = 0; j < size; j++) {
+                if (i == 0 && j == 0) sumArr[i][j] =  arr[i][j];
+                else if (i == 0) sumArr[i][j]=  sumArr[i][j-1] + arr[i][j];
+                else if (j == 0) sumArr[i][j]  =  sumArr[i-1][j] + arr[i][j];
+                else sumArr[i][j] = sumArr[i-1][j] + sumArr[i][j-1] + arr[i][j] - sumArr[i-1][j-1];
+
+            }
+        }
+
+
+    }
+
+
+    private static void print() {
+        System.out.println(ans);
+    }
+}
+
+
+```