[20250814] BOJ / G5 / 사과나무 / 이인희

Author: LiiNi-coder

LiiNi-coder/202508/14 BOJ 사과나무.md

@@ -0,0 +1,64 @@
+```java
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.Arrays;
+
+public class Main {
+	private static BufferedReader br;
+	private static int N;
+	private static int[][] Map;
+	public static void main(String[] args) throws IOException {
+		br = new BufferedReader(new InputStreamReader(System.in));
+		N = Integer.parseInt(br.readLine());
+		Map = new int[N+1][N+1];
+		for(int r = 1; r < N+1; r++){
+			String[] temp = br.readLine().split(" ");
+			for(int c = 1; c<N+1; c++){
+				Map[r][c] = Integer.parseInt(temp[c-1]);
+			}
+		}
+
+		int answer = Integer.MIN_VALUE;
+		//누적합 구하기
+		var preMap = new int[N+1][N+1];
+		for(int r = 1; r < N+1; r++){
+			for(int c = 1; c < N+1; c++){
+				preMap[r][c] = Map[r][c] + preMap[r-1][c] + preMap[r][c-1] - preMap[r-1][c-1];
+			}
+		}
+
+		// for(int[] line: preMap){
+		// 	System.out.println(Arrays.toString(line));
+		// }
+
+
+		for(int r = 1; r<N+1; r++){
+			for(int c = 1; c<N+1; c++){
+				for(int n = 0; n<N+1; n++){
+					int[] rightDown = new int[2];
+					rightDown[0] = r+n;
+					rightDown[1] = c+n;
+					if(rightDown[0] >= N+1 || rightDown[1] >= N+1){
+						continue;
+					}
+
+					int partitialSum;
+					if(n == 0){
+						partitialSum = Map[r][c];
+					}else{
+						partitialSum=
+						preMap[rightDown[0]][rightDown[1]]
+						- preMap[rightDown[0] - (n+1)][rightDown[1]]
+						- preMap[rightDown[0]][rightDown[1] - (n+1)]
+						+ preMap[r-1][c-1];
+					}
+					answer = Math.max(answer, partitialSum);
+					//System.out.println(String.format("(r, c)=(%d, %d) (rd0, rd1)=(%d, %d), partitialSum: %d", r, c, rightDown[0], rightDown[1], partitialSum));
+				}
+			}
+		}
+		System.out.println(answer);
+	}
+}
+```