Largest Plus Sign

https://www.lintcode.com/problem/largest-plus-sign/description

import java.util.Arrays;

public class Solution {
    private int result = 0;
    /**
     * @param N: size of 2D grid
     * @param mines: in the given list
     * @return: the order of the plus sign
     */
    public int orderOfLargestPlusSign(int N, int[][] mines) {
        // Write your code here
        int[][] grid = new int[N][N];
        for (int i = 0; i < grid.length; i++) {
            int[] ints = grid[i];
            Arrays.fill(ints, 1);
        }
        for (int i = 0; i < mines.length; i++) {
            int[] mine = mines[i];
            grid[mine[0]][mine[1]] = 0;
        }
        for (int i = 0; i < grid.length; i++) {
            int[] mine = grid[i];
            for (int j = 0; j < grid.length; j++) {
                if (mine[j] == 1) {
                    treeWalk(grid, i, j);
                }
            }
        }
        return result;
    }

    private void treeWalk(int[][] mines, int i, int j) {
        int level = 1;
        while (true) {
            {
                int x = j - level;
                int y = i;
                if (x >= 0 && mines[y][x] == 1) {

                } else {
                    break;
                }
            }
            {
                int x = j + level;
                int y = i;
                if (x < mines[0].length && mines[y][x] == 1) {

                } else {
                    break;
                }
            }
            {
                int x = j;
                int y = i - level;
                if (y >= 0 && mines[y][x] == 1) {

                } else {
                    break;
                }
            }
            {
                int x = j;
                int y = i + level;
                if (y < mines.length && mines[y][x] == 1) {

                } else {
                    break;
                }
            }
            level++;
        }
        result = Math.max(level, result);
    }
}