https://leetcode.com/problems/island-perimeter/

package com.company;import java.util.*;class Solution {    public int islandPerimeter(int[][] grid) {        int ret = 0;        int[] x = {-1, 0, 1, 0};        int[] y = {
   0, 1, 0, -1};        for (int i=0; i
     
      = grid.length ||                                j+y[k] < 0 || j+y[k] >= grid[0].length ||                                grid[i+x[k]][j+y[k]] == 0) {                            ret++;                        }                    }                }            }        }        return ret;    }}public class Main {    public static void main(String[] args) throws InterruptedException {        System.out.println("Hello!");        Solution solution = new Solution();        // Your Codec object will be instantiated and called as such:        int[][] grid = {
   {
   0,1,0,0},{
   1,1,1,0},{
   0,1,0,0},{
   1,1,0,0}};        int ret = solution.islandPerimeter(grid);        System.out.printf("ret:%d\n", ret);        System.out.println();    }}