[20250727] BOJ / G5 / 제곱수 찾기.md

Author: Seol-JY

Seol-JY/202507/27 BOJ G5 제곱수찾기.md

@@ -0,0 +1,65 @@
+```java
+import java.io.BufferedReader;
+import java.io.InputStreamReader;
+import java.io.IOException;
+
+public class Main {
+    static int N, M;
+    static int[][] board;
+    static int maxSqrt = -1;
+
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+
+        String[] sizes = br.readLine().split(" ");
+        N = Integer.parseInt(sizes[0]);
+        M = Integer.parseInt(sizes[1]);
+
+        board = new int[N][M];
+        for (int i = 0; i < N; i++) {
+            String line = br.readLine();
+            for (int j = 0; j < M; j++) {
+                board[i][j] = line.charAt(j) - '0';
+            }
+        }
+
+        for (int row = 0; row < N; row++) {
+            for (int col = 0; col < M; col++) {
+                for (int dr = -N; dr <= N; dr++) {
+                    for (int dc = -M; dc <= M; dc++) {
+                        if (dr == 0 && dc == 0) continue;
+
+                        int r = row;
+                        int c = col;
+                        StringBuilder sb = new StringBuilder();
+
+                        while (r >= 0 && r < N && c >= 0 && c < M) {
+                            sb.append(board[r][c]);
+                            long num = Long.parseLong(sb.toString());
+
+                            if (isPerfectSquare(num)) {
+                                maxSqrt = Math.max(maxSqrt, (int) num);
+                                if (maxSqrt >= 31622 * 31622) {
+                                    System.out.println(maxSqrt);
+                                    return;
+                                }
+                            }
+
+                            r += dr;
+                            c += dc;
+                        }
+                    }
+                }
+            }
+        }
+
+        System.out.println(maxSqrt);
+    }
+
+    static boolean isPerfectSquare(long num) {
+        long sqrt = (long) Math.sqrt(num);
+        return sqrt * sqrt == num;
+    }
+}
+
+```