가장 큰 정사각형 찾기

package programmers;

public class 가장_큰_정사각형_찾기 {

   //위, 왼쪽대각, 왼쪽의 최솟값 + 1

   private static int[] dy = {-1, -1, 0};
   private static int[] dx = {0, -1, -1};

   public static int solution(int[][] board) {
      go(board);

      int ans = find(board);
      return ans * ans;
   }

   private static int find(int[][] board) {
      int ans = -1;

      for (int[] nums : board) {
         for (int j = 0; j < board[0].length; j++) {
            ans = Math.max(ans, nums[j]);
         }
      }

      return ans;
   }

   private static void go(int[][] board) {
      for (int i = 1; i < board.length; i++) {
         for (int j = 1; j < board[0].length; j++) {
            if (board[i][j] > 0) {
               int min = Integer.MAX_VALUE;
               for (int k = 0; k < 3; k++) {
                  int ny = i + dy[k];
                  int nx = j + dx[k];
                  min = Math.min(min, board[ny][nx]);
               }
               board[i][j] = min + 1;
            }
         }
      }
   }

   public static void main(String[] args) {
      System.out.println(solution(new int[][] {{0, 1, 1, 1}, {1, 1, 1, 1}, {1, 1, 1, 1}, {0, 0, 0, 0}}));
      System.out.println(solution(new int[][] {{0, 0, 1, 1}, {1, 1, 1, 1}}));

   }
}