764. Largest Plus Sign

https://leetcode.com/problems/largest-plus-sign/description/

解题思路：

1. 判断当前dp[i][j]的最大plus sign by using while(j-dir>=0 && j+dir<N && i-dir>=0 && i+dir<N && grid[i][j-dir]==1 && grid[i][j+dir]==1 && grid[i-dir][j]==1 && grid[i+dir][j]==1)

代码如下：
class Solution {
public int orderOfLargestPlusSign(int N, int[][] mines) {

    int[][] grid = new int[N][N];
    int ans = 0;
    for(int i = 0; i < N; i++){
        Arrays.fill(grid[i], 1);
    }
    for(int[] m : mines){
        grid[m[0]][m[1]] = 0;
    }
    for(int i = 0; i < N; i++){
        for(int j = 0; j < N; j++){
            if(grid[i][j] == 1){
                int dir = 1;
                while(j-dir>=0 && j+dir<N && i-dir>=0 && i+dir<N && grid[i][j-dir]==1 && grid[i][j+dir]==1 && grid[i-dir][j]==1 && grid[i+dir][j]==1){
                    dir++;
                }
                ans = Math.max(ans, dir);
            }
        }
    }
    return ans;
}

}